Apparatus and methods usable in connection with dispensing flexible sheet material from a roll

ABSTRACT

A powered dispenser for dispensing individual sheet segments from a continuous roll of sheet material provided with spaced tear lines comprises a powered feed mechanism, a releasable, powered drive mechanism, a powered transfer mechanism, a pair of web sensing sensors, a capacitive sensing system providing automatic sensitivity adjustment, and control circuitry. A dual power supply system provides a mechanical lock-out functionality, and the control system is protected from electrostatic build-up on the surface of the feed roller. The web sensor, and an antenna plate of the capacitive sensing system, are provided on respective printed circuit boards mounted in overlying relation. Utilizing signals received from the pair of web sensors and the capacitive sensing system, the control circuitry senses the presence of a user to activate the powered drive mechanism, and prevents further dispensing of the sheet material until a previously dispensed segment is separated from the roll. The web sensors detection of a leading edge of the sheet material initiates a predetermined interval of sheet material advancement providing a proper placement of successive tear lines. Various approaches may be utilized to accommodate inadvertent sheet “tabbing” scenarios. The web sensors, together with the control circuitry, are also used to detect the depletion, or absence, of a working roll of sheet material, whereupon the control circuitry controls the powered transfer mechanism to automatically transfer the web feed supply from a depleted working roll to a reserve roll. The powered transfer mechanism may include a motor driven transfer bar, or provide motor driven release of a spring biased transfer bar. Another arrangement allows for ready release of a roll core, and drop of the same into an open dispenser cover for removal.

This application is a divisional of U.S. application Ser. No.10/092,350, filed on Mar. 7, 2002.

FIELD OF THE INVENTIONS

The present inventions relate to the dispensing of flexible sheetmaterial from a roll. In particular, the present inventions relate tovarious features that may be advantageously used by themselves or inconjunction with each other, in connection with the dispensing of webproducts (e.g., paper towels or napkins) from a roll in an institutionalsetting. A proximity sensing circuit and method in accordance with oneinvention may be advantageously applied in virtually any applicationwhere it is desired to detect the presence or proximity of a user orobject relative to something else. The inventions described hereincompliment each other as well as: the powered dispensing and usersensing related inventions disclosed in co-pending commonly owned patentapplication Ser. No. 09/081,637, filed May 20, 1998; and the poweredfeed transfer related inventions described in co-pending commonly ownedapplication Ser. No. 09/604,811, filed Jun. 28, 2000.

BACKGROUND OF THE INVENTIONS

Dispensers for toweling have primarily fallen into one of threecategories: those that dispense segments of a continuous (endless)towel, those that dispense individual folded paper towels, and thosethat dispense towel segments separated from a roll of paper sheetmaterial. Continuous towels are generally made of a reusable materialand form a towel loop outside of the dispenser cabinet that may begrasped for use. Folded paper towels are generally pre-cut and foldedinto various configurations to be individually dispensed for use. Rollsof paper toweling are generally wound around a central core. Upondispensing, segments of the sheet material are delivered from thedispenser and separated from the roll by tearing or cutting performed bythe dispenser and/or the user.

Continuous web dispensers, such as those disclosed in U.S. Pat. No.2,930,663 to Weiss and U.S. Pat. No. 3,858,951 to Rasmussen, require theuser to pull on the loop of exposed toweling in order to cause a lengthof clean toweling to be dispensed and the exposed soiled toweling to becorrespondingly taken up within the dispenser. Although economical, thecontinuous exposure of the soiled toweling is deemed unsightly and,therefore, unacceptable to many consumers when compared to the manyavailable alternatives. Further, the exposure and possible reuse ofsoiled toweling may present additional health hazards and sanitationconcerns which should be avoided.

The use of interfolded paper towels or C-fold paper towels eliminatesthe potential health risks associated with continuous web toweling. Forinstance, dispensers for folded paper towels, such as disclosed in U.S.Pat. No. 3,269,592 to Slye et al., allow a user to dispense the towelsby pulling on the exposed end of each new individual towel. Thesedispensers are also easy to refill with folded towels. However, a numberof the folded towels will sometimes drop out of the lower opening of thedispenser when only the exposed towel is pulled, especially when thestack of towels in the dispenser is small. This can result in asignificant waste of paper towels. Accordingly, folded towels are not aseconomical as other kinds of alternative dispensers.

Roll towels are cheaper to manufacture and produce less waste thanfolded towels. Roll towels also eliminate the potential health andsanitation problems associated with continuous web toweling systems.Dispensers for roll towels may include a lever, crank, or otheruser-activated mechanism for dispensing a length of towel, and a bladefor severing the length of towel from the remaining roll. However, ascan be appreciated, manual contact with a dispensing lever or the likeraises health concerns for the user. To alleviate these health concerns,dispensers, such as U.S. Pat. No. 4,712,461 to Rasmussen, eliminatecontact with any part of the dispenser, and instead rely upon the userdirectly pulling the paper towel out of the dispenser. As a result, thepaper towel must be provided with sufficient strength to effect rotationof the feed roller and actuation of the blade without premature tearing.Paper possessing the requisite strength to operate the dispenser islimited in the amount of softness and absorbency which can be providedto the paper towels.

Dispensers for roll towels have also been electrically powered. As shownin U.S. Pat. No. 5,452,832 to Niada, a light sensitive device is used todetect the presence of a user's hand in front of the dispenser andadvance the toweling for a predetermined length of time. The dispensedlength of paper towel is then separated from the continuous web bypulling the paper against a serrated cutting member. While the feedroller is powered, the cutting action still requires the paper topossess a certain minimum strength and generally produces a rough,unsightly cut.

U.S. Pat. No. 4,738,176 to Cassia discloses an electrically powereddispenser which also includes a reciprocating cutter to produce anindividual towel from the continuous web of paper. While thisarrangement enables the use of softer and more absorbent paper, thedispenser requires a substantial amount of energy to drive the feedmechanism and the reciprocating cutter. Accordingly, the batteries mustbe replaced relatively frequently. Moreover, the system is more complexand costly with its use of one-way clutches.

Also, in some electrically powered dispensers, such as U.S. Pat. No.4,796,825 to Hawkins, the paper will continually dispense while a handor other object is placed in front of the sensor. Hence, the dispenseris subject to easy abuse and waste of paper. Moreover, some dispensersare subject to dispensing paper by the general proximity of a personirrespective of whether a paper towel is needed. In an effort to avoidabuses, some dispensers, such as U.S. Pat. No. 4,666,099 to Hoffman,have incorporated a waiting period where the dispenser will not operatefor a brief time after each use. However, the need to wait can befrustrating to users under some circumstances.

Previously mentioned copending application Ser. No. 09/081,637 disclosesan electric motor powered dispenser which overcomes many of thedisadvantages of the prior art described above. For example, in oneaspect, the dispenser facilitates the dispensing of a roll of paper withspaced apart transverse lines of tearing (e.g. perforation lines) foreasily separating individual sheets from the continuous roll withoutcutting. As a result, paper with a high degree of softness andabsorbency can be used without the high energy demands required by areciprocating cutter. In another aspect, the dispenser senses theleading edge of the continuous web of paper material to initiate acontrol device which controls the length of each segment of paper. Inthis way, the dispenser can always place the transverse tearing line atthe proper position in relation to the discharge opening for eachdispensed sheet, irrespective of variations of the spacing for thetearing lines within a tolerance range. In another aspect, the dispenserincludes a sensor for sensing the presence of a sheet that has beendispensed, but not removed, in order to prevent the dispenser fromdispensing any more sheets until the previous sheet has been torn off.In this way, abuse of the dispenser and waste of the paper material canbe minimized without requiring the use of a waiting period wherein thedispenser will not operate. Accordingly, the dispenser is always readyfor use.

Other systems have been developed for sensing the proximity of, forexample, a hand to a dispenser for controlling dispensing of an item,such as paper towels, water, hand soap, etc. For example, U.S. Pat. No.5,694,653 to Harald discloses a system that senses the proximity of aperson's hands to a water faucet, thereby providing hands-free operationof the faucet. According to Harald, the spout of a water faucet iscoupled to an oscillator and functions like a transmitting antenna byemitting a time-varying primary electrostatic field. When a person'shands are placed in the primary electrostatic field in proximity of thespout, the person's body begins to radiate a secondary field insyncopation with the primary field. A receiver antenna located away fromthe spout, such as behind the front panel of a vanity, receives thesecondary field, which is processed for turning on the water. Severaldifferent receiver antennas can be used for detecting the relativeposition of a hand with respect to a particular receiver antenna forcontrolling, e.g., the temperature of the water. To provide sufficientsensitivity so that proximity of a hand with respect to the Haraldsensor system operates reliably, the signal driving the faucet spoutmust be shielded from the receiving antennas. Additionally, thereceiving antennas must be oriented and shielded to avoid detecting theprimary field.

U.S. Pat. No. 6,279,777 B1 to Goodin et al. discloses another hands-freeproximity sensing system for a dispenser. According to Goodin et al., aproximity sensing system includes a theremin sensor and a second sensor,such as a conventional infrared, ultrasonic, heat, light, proximity oraudio sensor detector, for detecting the presence of a human body partin proximity to the dispenser. The theremin sensor includes twoclosely-spaced antenna panels that establish a capacitance therebetweenindependent of a ground connection. The antenna panels are coupled to anoscillator circuit that oscillates at a frequency related to thecapacitance established between the two panels. When a person's handcomes into close proximity of the panels, the capacitance provided bythe persons' hands increases the capacitance between the two antennapanels, and thereby changes the frequency of oscillation and a firstoutput signal is generated. The second sensor independently senses thepresence of the person's hand and also generates a second output signal.The dispenser, in response to the first and second output signals,performs a dispensing operation. While the Goodin et al. sensing systempurports to provide high reliability in avoiding false sensingsituations, it is apparent that the stray capacitance provided by theenvironment in which a Goodin et al. sensor is installed may adverselyaffect the frequency of oscillation of the oscillator such that theoscillator circuit must be calibrated so that the sensitivity of thetheremin sensor can reliably sense the change in capacitance provided bya person's hand.

As described above, roll towel dispensers may utilize a manual drivemechanism such as a user operated crank or lever to drive a feedmechanism to dispense the towels, or alternatively a powered drivemechanism. In either case, the feed mechanism typically will include adrive roller and a pressure roller, also known as a pinch roller, whichform a nip. When the rolled paper runs out in a conventional rolldispenser, an attendant must replace the roll and manually insert theleading edge of the new roll into the nip. This can require complextowel threading and loading sequences. After the attendant has placedthe leading edge of the roll into the nip, the feed mechanism isoperated in order to advance the leading edge through the feedmechanism, thereby causing a length of paper towel to be unwound fromthe roll core and delivered to the user.

In contrast to folded paper towel dispensers, conventional roll toweldispensers do not provide an economical way to replenish the towelsupply when a partially depleted roll, i.e., a “stub” roll, remainswithin the dispenser. In some prior art dispensers, a new roll must besubstituted for the stub roll, thereby resulting in the waste ofwhatever paper remains on the stub roll. This can result in increasedoperational costs as a significant amount of paper may be wasted infacilities with many dispensers. To overcome the problem of stub rollwaste, other roll dispensers have been designed to dispense two rolls ofweb material sequentially such that upon depletion of a primary roll,feeding from a reserve roll is commenced.

Prior art systems have accomplished this transfer by either modifyingthe end of the web material or modifying the roll core upon which theweb material is wound, such as the system disclosed in U.S. Pat. No.3,288,387 to Craven, Jr. Alternatively, the systems of U.S. Pat. No.3,628,743 to Bastian et al. and U.S. Pat. No. 5,294,192 to Omdoll et al.sense the diameter of the primary roll in order to activate the transferto the reserve roll, and the system of U.S. Pat. No. 3,917,191 toGraham, Jr. et al. senses the tension in the primary roll in order todetect when it is nearly exhausted. Unfortunately, tension responsivetransfers are not particularly reliable since conditions other thanreaching the end of the roll can trigger their operation, such as theslackening of the web or a break in the web material. Diameterresponsive transfers also have a drawback in that the reserve web beginsdispensing prior to the complete exhaustion of the primary roll. Thus,for a short time web material is dispensed simultaneously from bothrolls and again results in a waste of material.

In efforts to overcome these disadvantages, the systems of U.S. Pat. No.4,165,138 to Hedge et al., U.S. Pat. No. 4,611,768 to Voss, et al., andU.S. Pat. No. 4,378,912 to Perrin et al. provide transfer mechanismsthat sense the absence or presence of paper from around a feed roll. Inone system, this is accomplished by a sensing finger which rides alongthe top surface of the web material and then drops down into a groove inthe feed roll which is exposed when the trailing end of the primary webhas been unwound from the roll. In response to the sensing finger movinginto the groove, the reserve web is introduced into the feed nip betweenthe drive roller and the pressure roller, and the dispenser begins tofeed the reserve roll to the user. This type of transfer mechanismgenerally eliminates the false transfers associated with tensionresponsive systems and reduces the amount of double sheet dispensingwhich occurs in diameter sensing transfer systems. The use of sensingfingers on the web material, however, produces extra friction which caninadvertently tear the web. Moreover, the introduction of additionalcomponents to sense the absence of the web and transfer the reserve webto between the feed rollers creates opportunities for a transfer failureto occur.

A need has therefore existed for a flexible sheet dispenser having anautomatic transfer mechanism which, in addition to substantiallyeliminating simultaneous dispensing from both primary and reserve rolls,requires few additional parts within the dispenser and which is notprone to interference with the proper dispensing of either the workingor reserve roll web material. A transfer mechanism that, to a largeextent, fulfills this need is described in commonly assigned U.S. Pat.No. 5,526,973 to Boone et al. Therein, movement and interengagement ofone grooved feed roller relative to the other upon depletion of a stubroll, actuates a transfer mechanism that introduces a reserve web intothe feed nip. While generally quite effective, the movement and springbiasing of a relatively high mass feed roller can lead to difficulties.The feed roller spring bias force must be within a relatively narrowwindow. If the spring bias is set too high, the biasing force mayinhibit smooth feeding of the web material through the rollers, andresult in tearing of the web material. If it is set too low, themechanism may not actuate effectively to cause a transfer of feed to thereserve roll immediately upon depletion of the stub roll. Over time, thespring bias provided to move one roll relative to the other is prone toeventually decrease, e.g., due to fatigue of the spring, such thatultimately the spring force may fall below the required relativelynarrow range and thus be insufficient to properly actuate a webtransfer.

Previously mentioned co-pending application Ser. No. 09/604,811discloses a dispenser having an electric motor powered transfermechanism that overcomes many of the disadvantages of the prior artdescribed above. That dispenser can provide hands free, automaticfeeding of a first sheet of a primary web roll, such as a paper towelroll, into a feed mechanism when its cover is closed. The dispenser canalso automatically transfer its web feed supply from a working roll to areserve roll upon the exhaustion of the working roll. The designeliminates the need for an attendant to thread the leading edge of aroll into the feed mechanism of the dispenser. It also reduces wastedpaper because it does not begin to feed from a reserve roll until theworking roll has been fully depleted. The dispenser includes a chassishaving a web discharge opening and a feed mechanism for advancing theweb to the web discharge opening. The dispenser also includes a sensorfor determining when a portion of the web is absent from a side of thefeed mechanism proximate the web discharge opening. When such an absenceis sensed, an automatic, powered web transfer mechanism contacts the weblocated in front of the feed mechanism and positions it in the feed nip,i.e., between the rollers of the feed mechanism. The transfer mechanismincludes a web transfer member and a motor for driving the transfermember in the direction of the feed mechanism. The dispenser alsoincludes a retraction mechanism for returning the transfer bar to a restposition after the web has been introduced into the feed mechanism.

SUMMARY OF THE INVENTIONS

The present inventions arose out of efforts to develop a “nextgeneration” sheet material dispenser providing increased convenience andsimplicity of use and maintenance. In particular, it was an object ofthe inventors to provide a dispenser capable of carrying out dispensingoperations in a reliable and controlled manner that would avoid the needfor a user to make physical contact with the dispenser. The inventorsalso sought to develop a dispenser that would, by virtue of its variousfeatures, minimize dispenser downtime due to depletion of the dispensedroll material or the dispenser power supply, or due to jams of the feedmechanism. Moreover, the inventors sought to develop a dispenser thatwould improve the efficiency of institutional/building maintenanceoperations, by facilitating dispenser maintenance by unskilledpersonnel.

It is an object of one of the present inventions to provide a proximitysensing system that senses the proximity of a person's hand or otherbody part, based on the capacitance provided by the body part, and thatautomatically compensates for environmental changes by adjusting thesensitivity of the sensor so that changes in capacitance provided by aperson's hand (or other body part) are reliably sensed, regardless ofthe variations in stray capacitance provided by the environment in whichthe proximity sensor is placed.

One or more of the above, and/or other objects, are achieved by thevarious inventions disclosed and claimed herein.

According to a first one of the inventions, a dispenser is provided fordispensing flexible sheet material. The dispenser includes a support forrotatably supporting a roll of sheet material. A feed mechanism isprovided for advancing the sheet material out of the dispenser. A drivemember is provided for driving the feed mechanism. The drive member ismovably mounted for movement into and out of engagement with the feedmechanism. A hold mechanism is provided for holding the drive member inengagement with the feed mechanism. The hold mechanism is manuallyreleasable to permit the drive member to be moved out of engagement withthe feed mechanism.

According to a second one of the inventions, a drive mechanism assemblyis provided for selectively engaging with and driving a feed mechanismof a flexible sheet material dispenser. The drive mechanism assemblyincludes a motor having a drive shaft, and a drive member attached tothe drive shaft for drivingly engaging the feed mechanism in anengagement position. A carrier retains therein the motor and the drivemember. The carrier includes a rotatable mounting member for rotatablymounting the motor and drive member to a dispenser chassis for rotationas a unit into and out of the engagement position.

According to a third one of the inventions, a method of removing a jamfrom a dispenser for dispensing flexible sheet material is provided. Asheet material jam is detected. A drive mechanism of the dispenser isdisengaged from a feed mechanism of the dispenser. The jam is clearedfrom the path of the feed mechanism by rotating the feed mechanism whileit is disengaged from the drive mechanism. The drive mechanism is thenreengaged with the feed mechanism.

According to a fourth one of the inventions, a dispenser for dispensingflexible sheet material includes a feed mechanism, a drive mechanism forselectively driving the feed mechanism, and a control device forcontrolling the drive mechanism. A battery container is provided forremovably holding at least one battery for powering at least one of thedrive mechanism and the control device. A power line input port isprovided, to which a power line may be connected to supply power to atleast one of the drive mechanism and the control device in lieu ofbattery power. The power line input port is arranged in relation to thebattery container such that (1) when the battery container is loadedwith the at least one battery to supply power to at least one of thedrive mechanism and the control device, the line input port is preventedfrom being connected to the power line; and (2) when the batterycontainer is unloaded, the power line input port is readily accessiblefor connection of the power line.

According to a fifth one of the inventions, a dispenser for dispensingflexible sheet material includes a support for rotatably supporting aroll of sheet material, a feed mechanism for advancing the sheetmaterial from the roll, and a motor for driving the feed mechanism. Astructure defines a discharge chute of the dispenser downstream of thefeed mechanism. A sensor is provided for detecting the presence andabsence of sheet material in the discharge chute and outputtingrespective first signals indicative thereof. A proximity sensing systemincluding an RF antenna is provided for detecting the presence of auser's hand in close proximity to the dispenser, and outputting a secondsignal indicative thereof. A control device is provided for receivingthe respective first signals, and the second signal, and for controllingthe motor to selectively drive the feed mechanism in response thereto.The sensor is mounted on a first printed circuit board mounted on thestructure adjacent to the discharge slot. The antenna is mounted on asecond printed circuit board mounted on the structure and positioned inoverlying relation to the first printed circuit board.

According to a sixth one of the inventions, a dispenser for dispensingflexible sheet material includes a support for rotatably supporting aroll of sheet material. A feed mechanism is provided for advancing thesheet material from the roll. A motor is provided for driving the feedmechanism, and a structure defines a discharge chute of the dispenserdownstream of the feed mechanism. A transfer mechanism is provided forcontacting a leading segment of sheet material extending from a roll,and for moving the sheet material into a feed nip of the feed mechanism.A sensor is provided for detecting the presence and absence of sheetmaterial in the discharge chute and outputting respective signalsindicative thereof. A control device is provided for receiving therespective signals, and for controlling the motor to selectively drivethe feed mechanism in response thereto, to dispense a predeterminedlength of the sheet material from the point at which a leading edgeportion is detected by one of the plurality of sensors. The controldevice further determines, based upon the signals, a condition wherein aworking roll of sheet material is either absent or depleted, and inresponse to that determination controls the transfer mechanism toattempt a transfer of feed to a new roll of sheet material.

According to a seventh one of the inventions, a dispenser for dispensingflexible sheet material includes a support for rotatably supporting aroll of sheet material, a feed mechanism for advancing the sheetmaterial from the roll, and a motor for driving the feed mechanism. Aplurality of sensors are spaced along a width of the sheet material fordetecting respective leading edge portions of the sheet material andoutputting respective signals indicative thereof. A control device isprovided for receiving the respective signals and controlling the motorto drive the feed mechanism to dispense a predetermined length of thesheet material from the point at which a leading edge portion is firstdetected by one of the plurality of sensors.

According to an eighth one of the inventions, a dispenser for dispensingflexible sheet material includes a support for rotatably supporting aroll of sheet material, a feed mechanism for advancing the sheetmaterial from the roll, and a motor for driving the feed mechanism. Asensor is provided for detecting a leading edge portion of the sheetmaterial and outputting a signal indicative thereof. A measurementdevice is provided for measuring a first interval of advancement of thefeed mechanism terminating with a detection of a leading edge portion bythe sensor. A control device is provided for receiving signals from thesensor and the measurement device, and for controlling the motor todrive the feed mechanism to dispense a predetermined length of the sheetmaterial from a determined initialization point. The control deviceincludes a storage device for storing a nominal measure of the firstinterval of advancement, a comparator for comparing a measurement of themeasurement device with the nominal value, and determination means fordetermining the initialization point for a given dispense cycle basedupon an output of the comparator.

According to a ninth one of the inventions, a dispenser includes ahousing having a discharge opening. A support is provided within thehousing for supporting a continuous strip of sheet material having aplurality of spaced tear lines defining leading and trailing edges ofindividual removable segments, with an outer segment having a freeleading edge and inner segments which in turn become outer segments asadjoining outer segments are removed. A feed mechanism is provided forrepeatedly moving the sheet material in advancement and retractionintervals. The advancement intervals serve to advance successive outerones of the segments through the discharge opening and out of thehousing. The retraction intervals serves to initialize the sheetmaterial for the advancement interval. A sensor is provided forrepeatedly detecting arrival of a leading edge of retracting sheetmaterial at a first position defining the end of the retraction intervaland the beginning of the advancement interval, as sheet material isrepeatedly retracted back into the discharge opening. A control deviceis provided for receiving a signal from the sensor indicating an arrivalof a leading edge at the first position, and for initiating theadvancement interval from the first position. The advancement intervalterminates when the leading edge of the sheet material has advanced fromthe first position a pre-determined amount, to repeatedly place thespaced tear lines at a second position that is variable downstream ofthe first position in relation to variations in the lengths of thesegments. The second position defines the beginning of a retractioninterval for a next adjacent segment, when it is in turn initialized foran advancement interval.

According to a tenth one of the inventions, a dispenser for dispensingflexible sheet material from a roll includes a chassis defining a webdischarge opening and a feed mechanism for advancing the sheet materialto the discharge opening. A detection system is provided for detectingan absence of sheet material within the feed mechanism. A transfermechanism is provided for contacting a leading segment of sheet materialextending from a roll and moving the sheet material into a feed nip ofthe feed mechanism. The transfer mechanism includes a transfer memberbiased toward the feed nip and into contact with the leading segment ofsheet material. A transfer link is movable between a first positionwherein the transfer link retains the transfer bar away from the feednip, against the bias, and a release position wherein the transfer linkpermits the transfer member to move toward the feed nip under the biasand into contact with the leading segment of sheet material. Anactuator, e.g., a motor, is provided for driving the transfer link fromthe first position to the release position. Control means are providedfor electrically activating the actuator to drive the transfer link fromthe first position to the release position in response to the detectionsystem detecting an absence of sheet material within the feed mechanism.

According to an eleventh one of the inventions, a dispenser fordispensing flexible sheet material includes a chassis defining a gap forpassage of a sheet material roll core therethrough. At least onefinger-operable, releasable support mechanism is connected to thechassis for rotatably supporting the core above the gap. The support ismovable from a core retention position to a core release position forreleasing the core into the gap. A dispenser cover is movably mounted tothe chassis for movement between a closed position and an open position.The cover is situated, when in the open position, to receive a coredropped through the gap.

In a twelfth one of the present inventions, a proximity sensor circuitincludes an antenna, an oscillator circuit and an automatic sensitivitycontrol circuit. The antenna has a baseline stray capacitance. Theoscillator circuit is coupled to the antenna and generates anoscillation signal having a predetermined oscillation amplitudecorresponding to the baseline stray capacitance of the antenna.Preferably, the oscillator circuit has a Colpitts oscillator-typetopography. The oscillation amplitude of the oscillation signalincreases in response to an increase in stray capacitance from thebaseline stray capacitance of the antenna and decreases in response to adecrease in stray capacitance from the baseline stray capacitance of theantenna. The automatic sensitivity control circuit is coupled to theoscillator circuit and detects a change in the oscillation amplitude ofthe oscillator signal.

According to preferred embodiments of this invention, the automaticsensitivity control circuit controls the amplitude of the oscillatorsignal by controlling a current in the oscillator circuit, therebycounteracting a change in stray capacitance from the baseline straycapacitance of the antenna and maintaining the oscillation amplitude ofthe oscillator signal at the predetermined oscillation amplitude, toprovide a substantially constant sensitivity to changes in straycapacitance from the baseline stray capacitance of the antenna. Theproximity sensor circuit preferably generates a detect signal when theautomatic sensitivity control circuit detects an increase in theoscillation amplitude of the oscillator signal, such as when a hand isplaced in proximity to the antenna. A shield is preferably coupled toand driven by the oscillator circuit, thereby reducing the baselinestray capacitance of the antenna by an amount that may be about twoorders of magnitude greater than an increase in stray capacitance sensedby the proximity sensor circuit for generating the detect signal.

In a thirteenth one of the present inventions, a method is provided forproviding substantially constant sensitivity for sensing changes in abaseline stray capacitance to an antenna. According to this invention,an oscillation signal is generated by an oscillator circuit, preferablyhaving a Colpitts oscillator-type topography, and coupled to theantenna. The oscillation signal has a predetermined oscillationamplitude corresponding to the baseline stray capacitance of theantenna. The oscillation amplitude of the oscillation signal increase inresponse to an increase in stray capacitance from the baseline straycapacitance of the antenna and decreases in response to a decrease instray capacitance from the baseline stray capacitance of the antenna. Achange in the oscillation amplitude of the oscillator signal ispreferably detected and the amplitude of the oscillator signal ispreferably controlled by controlling a current in the oscillator circuitto counteract the detected change in stray capacitance from the baselinestray capacitance of the antenna. The oscillation amplitude of theoscillator signal is maintained at the predetermined oscillationamplitude to provide a substantially constant sensitivity to changes instray capacitance from the baseline stray capacitance of the antenna. Adetect signal is preferably generated when an increase in theoscillation amplitude is detected, such as when a hand is placed inproximity to the antenna. The oscillator circuit may include a shieldthat is driven with a signal related to the oscillation signal, therebyreducing the baseline stray capacitance of the antenna by an amount thatmay be about two orders of magnitude greater than an increase in straycapacitance that generates the detect signal.

According to a fourteenth one of the inventions, a dispenser fordispensing flexible sheet material from a roll includes a support forrotatably supporting a roll of sheet material having a plurality ofspaced apart tear lines defining individual segments of sheet material,a feed mechanism for advancing sheet material from the roll, and a motorfor driving the feed mechanism. A transfer mechanism is provided fortransferring a leading portion of a leading segment of the sheetmaterial into the feed mechanism, such that the leading portion isfolded over during the transfer to form a folded-over edge portion. Asensor is provided for detecting a leading edge of the sheet material. Acontrol means is provided for controlling application of power to themotor to drive the feed mechanism so as to carry out dispensingoperations wherein predetermined lengths of sheet material are dispensedfrom leading edges of the sheet material detected by the first sensor.The control means further controls operation of the transfer mechanism.In a first dispensing operation carried out by the control devicefollowing an operation of the transfer mechanism, the control devicecontrols the motor so as to carry out an initial dispensing operationwherein a first predetermined length of sheet material is dispensed fromthe point at which the leading edge is detected by the sensor, and tocarry out subsequent dispensing operations wherein a secondpredetermined length of sheet material larger than the firstpredetermined length is dispensed from the point at which subsequentleading edges are detected by the sensor, the difference between thefirst predetermined length and the second predetermined lengthcorresponding approximately to a length of the folded-over portion, suchthat a tear line between the first segment of sheet material and asecond segment of sheet material is, following the initial dispensingoperation, positioned between the feed mechanism and the first sensor,and subsequent tear lines between subsequent segments of the sheetmaterial are positioned between the feed mechanism and the first sensor,following subsequent dispensing operations.

According to a fifteenth one of the inventions, a dispenser fordispensing flexible sheet material includes a chassis, a support forrotatably supporting a roll of sheet material within the chassis, a feedmechanism for advancing the sheet material, and a motor for driving thefeed mechanism. A dispenser cover is movably mounted with respect to thechassis for movement between a closed position and an open position. Thecover has a surface defining a dispensing slot. The surface moves intooverlying registry with a discharge slot-defining portion of the chassiswhen the cover is moved into the closed position such that a leadingsegment of sheet material extending from the discharge slot when thecover is in the open position may become lodged between the cover andthe chassis when the cover is moved to the closed position. A sensor forsensing when the cover is in the open position and when the cover is inthe closed position. The sensor outputs a signal indicative thereof. Acontrol device is provided for controlling the motor to drive the feedmechanism so as to dispense a predetermined length of the sheet materialin response to the sensor indicating that the cover has been moved tothe closed position. The predetermined length of sheet material issufficient to cause a leading segment of sheet material lodged betweenthe chassis and the cover to loop out of the dispensing slot formed inthe cover.

The above and other objects, features and advantages of the presentinventions will be readily apparent and fully understood from thefollowing detailed description of preferred embodiments, taken inconnection with the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a roll towel dispenser embodying many ofthe present inventions, with a cover thereof pivoted to an openposition.

FIG. 2 is a perspective view of a chassis assembly of the dispensershown in FIG. 1, with parts exploded therefrom.

FIG. 3 is a rear side perspective view of the chassis assembly and partsshown in FIG. 2.

FIG. 4 is a right side elevational view of the dispenser shown in FIG.1, with the cover thereof pivoted to an open position.

FIGS. 5 and 6 are partially broken-away close-up side elevational viewsof a releasable drive mechanism of the dispenser shown in FIG. 1, inengagement and disengagement, respectively, with a driven gear of a feedmechanism of the dispenser.

FIG. 7 is an exploded perspective view of the releasable drive mechanismof FIG. 5.

FIG. 8 is a diagrammatic perspective view showing, in isolation, thereleasable drive mechanism engaged with the driven gear.

FIG. 9 is a partially broken-away left side elevational view of thedispenser shown in FIG. 1, with the cover thereof pivoted to an openposition and a roll core contained within the cover.

FIG. 10 is a cross-sectional view taken on line 10—10 in FIG. 9,illustrating an inventive power line input port/battery compartmentlock-out arrangement.

FIG. 11 is an exploded view of a front shield assembly of the dispensershown in FIG. 1, including overlying printed circuit boards providing,respectively, mounting surfaces for a pair of sheet detection sensors,and a proximity sensing system antenna.

FIG. 12 is a cross-sectional view taken on line 12—12 in FIG. 11,showing a discharge chute of the dispenser.

FIG. 13 is a diagrammatic front elevational view of a leading segment ofsheet material extending within the discharge chute of FIG. 12 and outof the dispenser, illustrating various “tabbing” scenarios.

FIG. 14 is a perspective view showing, a powered web feed transfermechanism of the dispenser of FIG. 1 in relation to the feed andpressure rollers of the dispenser.

FIG. 15 is a side elevational view of the web feed transfer mechanismand feed mechanism of FIG. 14.

FIGS. 16A–16E are diagrammatic side elevational views showing,sequentially, operation of an alternative web feed transfer mechanismproviding a powered release of a spring biased transfer bar.

FIG. 17 is a top plan view of the dispenser shown in FIG. 1, with thecover thereof pivoted to the open position.

FIG. 18 is a cross-sectional view illustrating a finger releasable rollcore support mechanism in accordance with one of the present inventions.

FIG. 19 shows a schematic diagram of a proximity sensor system used forsensing the proximity of a user's hand, according to one of the presentinventions.

FIG. 20 is a block diagram of an electrical control system that may beimplemented in the dispenser of FIG. 1.

FIGS. 21A and 21B are respective parts of a control flow diagram forprogram logic that may be implemented in conjunction with the electricalcontrol system of FIG. 20.

FIG. 22 is a bottom plan view of the dispenser of FIG. 1, with the coverthereof pivoted to a closed position.

FIG. 23 is a diagrammatic side elevational view of the dispenser of FIG.1, illustrating a loop of sheet material generated upon cover closure,in accordance with one of the present inventions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to FIGS. 1–3, a paper towel dispenser 1 according to thepresent invention comprises a chassis assembly 3 that includes a rightside chassis member 5, a left side chassis member 7, and a middlechassis member 9 extending between the side chassis members. Dispenser 1further includes a back panel member 11 and a pivotal front cover 13attached, by a pin 15, hinge or other convenient attachment mechanism,to back panel member 11. Front cover 13 may be opened and pivoted awayfrom chassis assembly 3 to a web loading position (as shown) allowing aroll 17 of a web material 18 to be loaded into dispenser 1.

In the illustrated exemplary embodiment, roll 17 comprises a continuousweb 18 of flat segments of paper towel material wound upon a hollowcylindrical core. Dispenser 1 could, of course, dispense other flexiblewebs, paper or otherwise. The web could, e.g., be in the form of foldedsheet segments wound onto a roll and separable from each other alonglines of perforation to form folded napkins. In the illustratedpreferred embodiment, web 18 of roll 17 includes a series of spacedapart, transverse tear lines 19 (one shown) which subdivide the web intoflat sheet (towel) segments of a predetermined length. Roll 17 isrotatably supported between an upper pair of supports. One of thesupports comprises an inwardly directed hub 21 attached to the free endof a spring arm 23 extending upwardly and inwardly along an inside ofright side chassis member 5 from a cantilever mounting point 25. Anopposite hub 27 (see FIG. 3) protrudes inwardly directly from an insideof left side chassis member 7. Each inwardly directed hub 21, 27 isloosely received within a core of roll 17 to permit free rotation ofroll 17. Of course, numerous other roll mounting arrangements could alsobe used.

To load a roll into dispenser 1, the attendant first opens front cover13 to the position shown in FIG. 1. Dispenser 1 is designed toaccommodate a working roll and a reserve roll. In the interest ofdispenser size reduction, the space defined between a lower pair of rollsupports 29, 31 of dispenser 1 is restricted such that a full roll (asmay be positioned in the upper pair of supports) cannot be placedtherein until after it has been depleted by about 60%. At such time, thepartially depleted working roll (now a stub roll) may be transferred byan attendant to lower set of supports 29, 31. As will be described indetail, this can be done while a leading portion of the towel webremains fed through the dispenser feed mechanism. Thereafter, a new(reserve) roll may be loaded into the upper pair of roll supports. Inother possible embodiments (having a larger space defined between lowerroll supports 29, 31), the attendant can have the option to initiallyload both rolls into the dispenser at the same time.

Middle chassis member 9 provides forms a foundation for a feed mechanismserving to dispense web 18 from roll 17 in incremental sheet segments.While the feed mechanism could be driven by a lever or the like, it ispreferably (and is shown) driven by an electric motor, generally in themanner described in copending application Ser. No. 09/081,637. In theillustrated preferred construction, the feed mechanism includes a matingfeed (drive) roller 33 and pressure roller 35 which cooperate todispense the web material. Feed roller 33 and pressure roller 35 aremounted upon axles rotatably supported at their ends by side chassismembers 5, 7. Pressure roller 35 is preferably biased against feedroller 33 by a spring (not shown) to define a feed nip 37. A gear (orother drive member) secured to a drive shaft of the motor is engageablewith a driven gear (or other driven member) secured to an axle of feedroller 33 to rotate the same. When web 18 is fed into nip 37, rotationof feed roller 33 causes web 18 to be advanced through nip 37, aroundfeed roller 33. Middle chassis member 9 provides at its rear side anarcuate guide plate 39 (see FIG. 3) to direct web 18 about the rear sideof feed roller 33 and into a discharge chute 41 (see FIG. 12) formedbetween middle chassis member 9 and a face plate structure 43 attachedthereto (seen in its entirety in FIG. 2). A discharge opening 45 isformed between a bottom forward edge of middle chassis member 9 and acorresponding lower portion of face plate structure 43 (see FIGS.22–23).

Releasable Feed Roller Drive Mechanism

Referring to FIGS. 4–8, a feed roller drive mechanism 47 according tothe present invention is now described in detail. Drive mechanism 47generally includes an electric motor 49, a drive member (in this case, aworm gear 51) and a carrier 53. Motor 49 is retained within carrier 53and has a drive shaft 55 to which worm gear 51 is attached. Carrier 53is pivotally connected to an outside of right side chassis member 5, ina manner permitting worm gear 51, which is also retained by carrier 53,to be moved into and out of driving engagement with a driven member (inthis case, a spur gear 57) of feed roller 33. In an engagement position,worm gear 51 mates with spur gear 57 for driving the same. A wormgear/spur gear set as illustrated provides a quiet, smooth and compactoutput system. In addition, by its inherent design, worm gear 51 cannotbe driven by spur gear 57. This one-way drive set-up advantageouslyavoids an overdrive of the feed mechanism due to a user pull on aleading segment of the sheet material being dispensed. Utilization of aworm gear also allows the motor drive shaft 55 to be orientedorthogonally with respect to feed roller 33, which allows for a morecompact dispenser design; it also permits easy engagement/disengagementwith spur gear 57. Other meshing gear sets may be used, as may otherknown means for transmitting rotary motion from one shaft to another,such as pressure rollers, belts, etc.

A pivotal mount of carrier 53 to right side chassis member 5 allowsmotor 49, drive shaft 55 and worm gear 51 to rotate as a unit into andout of driving engagement with spur gear 57, as shown by the arrow inFIG. 4. Although carrier 53 is shown pivotally attached to right sidechassis member 5, carrier 53 may be translatably or otherwise movablymounted to side chassis member 5, or to other suitable structure ofdispenser 1.

As best seen in FIG. 7, the pivotal carrier mount is provided by acylindrical sleeve 59 attached to a lower forward corner of a main bodyportion 61 of carrier 53. Sleeve 59 extends parallel to feed roller 33,and orthogonal to drive shaft 55 and attached worm gear 51. A bolt,screw rivet or like fastener 63 is passed through sleeve 59 andconnected to right side chassis member 5 to provide a carrier pivot axisextending within and along sleeve 59. Obviously, other known rotatablemounting arrangements may be used.

A spring clip arrangement 65 provides a releasable hold mechanism forremovably holding carrier 53 in a position, as shown in FIG. 5, whereinworm gear 51 is placed in driving engagement with spur gear 57. Springclip arrangement 65 is manually releasable (preferably finger operable)to allow carrier 53 to rotate worm gear 51 out of engagement with spurgear 57. As illustrated, spring clip arrangement 53 includes a springarm 67 extending forwardly from an upper part of carrier body portion61, and a stationary (female) retention clip 69 attached to an adjacentwall surface of right side chassis member 5. The free end of spring arm67 forms a (male) catch member 71 insertable into retention clip 69.Catch member 71 is offset relative to a primary lever portion 72 ofspring arm 67 so as to form at its rear side a shoulder 73. On its frontside, catch member 71 arcs downwardly such that a leading edge thereofis situated below the lever portion 72.

As illustrated, female retention clip member 69 is formed as a U-shapedframe attached to side chassis member 5 to thereby form a generallyrectangular opening that receives male catch member 71. As catch member71 is advanced into female clip member 69, the upper arcuate surface ofcatch member 71 slidably engages the top inner surface of clip member69. A cam action causes spring arm 67 to elastically deflect downwardly,thereby permitting catch member 71 to continue to advance into clipmember 69. Once fully inserted, an upper downstream edge 75 of therectangular frame acts as a latch surface that engages with shoulder 73.This engagement may be readily manually released by an attendant usinghis/her finger 77 to press downwardly on male clip member 69, to therebyelastically deflect spring arm 67 downwardly. As shown in FIG. 8, ascored, knurled or otherwise textured surface can be provided on the topside of catch member 71 to increase the friction between a pressingfinger and catch member 71 to thereby facilitate a releasingdisplacement of spring arm 67.

Referring to FIG. 7, carrier body portion 53 defines a motor chamber 79and a drive member chamber 81. A dividing wall structure 83 separatesthe two chambers and has a hole 85 formed through it. Drive memberchamber 81 is defined between dividing wall structure 83 and an oppositeend wall structure 87. A second hole 89 is formed in end wall structure87, in alignment with hole 85. Drive shaft 55 extends through, and isrotatable within, aligned holes 85 and 89. Dividing wall structure 83and end wall structure 87 thus serve to rotatably support drive shaft55. Motor 49 and drive shaft 55 may be restrained from backing out ofcarrier 53 by suitable means such as an e-clip 91 or other retentiondevice fixedly secured on the end drive shaft 55, outside of (and below)end wall structure 87.

Worm gear 51 is coaxially fixed on motor drive shaft 55 between dividingwall structure 83 and end wall structure 87. To permit drivingengagement of worm gear 51 and spur gear 57, the sidewall wall structuredefining drive member chamber 81 forms a side port 93 sized andpositioned to allow ingress and egress of a portion of spur gear 57to/from carrier 53 as carrier 53 is rotated into and out of itsengagement position.

Releasable drive mechanism 47 facilitates the clearing of jams that mayoccur in operation of dispenser 1, by permitting ready disengagement offeed roller 33 from motor 49. This functionality is accomplished with asimple structure having few parts, which are easily assembled. Carrier53 may be injection molded as a unitary thermoplastic component. Motor49, drive shaft 55 and worm gear 51 are readily engaged with each otherand within carrier 53 to complete the mechanism.

An attendant can readily disengage drive mechanism 47 by pressingdownwardly on catch member 71 to deflect spring arm 67 such that catchmember 71 is released from retention clip 69. Carrier 53 is then pivotedsuch that worm gear 51 moves out of engagement with spur gear 57. Theattendant may then rotate feed roller 33 and/or pressure roller 35 asnecessary to clear a jam. Once the jam is cleared, dispenser 1 may berestored to an operative state by simply re-engaging worm gear 51 withspur gear 57, by rotating carrier 53 in the opposite direction untilcatch member 71 is reengaged with female clip member 69. In contrast,with known motorized dispensers lacking provision for readydisengagement of the drive motor from the feed roller, jams must beremoved with the motor engaged, or a complicated procedure must beundertaken to disengage the drive motor and feed roller. Left engaged, adrive motor may impart significant additional drag inhibiting freerotation of the feed roller. As a result, manual rotation of the feedroller to remove a jam of web material may be rendered more difficult.As previously explained, utilizing a worm gear in the drive train as inthe present system precludes manual rotation of the feed roller withoutdisengagement of the drive motor.

Power Supply System

Referring now to FIGS. 9–10, a power supply system of dispenser 1includes a battery compartment 95 and a power line input port 97. Powerline input port 97 and battery compartment 95 are configured to providepower to the electrical systems and components of dispenser 1, to themutual exclusion of each other. Specifically, battery compartment 95 canonly receive a full complement of batteries (to complete a power supplycircuit) when power line input port 97 is not connected to a powerline/plug 99. Conversely, power line input port 97 can only receive apower line plug 99 when battery compartment 95 is not fully loaded andoperational.

As shown, battery compartment 95 is integrally formed as part of leftside chassis member 7 to receive standard size batteries, e.g., D-sizedry cells, arranged in a series connection between a pair of terminals101, 103. The compartment is closeable by way of a removable cover 105.Power line input port 97 is located directly adjacent to batterycompartment 95, at a lower side thereof. Access to port 97 is provided,preferably exclusively, through (from the inside of) battery compartment95. In the illustrated exemplary embodiment, power line input port 97 isa conventional DC input jack designed to receive output plug 99 of aconventional AC/DC power converter (adapter).

In accordance with the invention, power line input port 97 is configuredrelative to battery compartment 95 such that a power line 105 whenextending to plug 99 is engaged with power line input port 97 extendingfrom plug 99 naturally occupies a portion of battery compartment 95 andthereby precludes insertion of one or more batteries into thecompartment. Conversely, when battery compartment 95 is fully loadedwith batteries, access to power line input port 97 is blocked and port97 is prevented from being connected to power plug/line 99, 105.

The above-described power supply arrangement of dispenser 1 provides afacility owner/operator with the option to choose two dispenser powersources—battery and line power. This allows greater flexibility in theuse and location of the dispenser. At the same time, potential damage toor malfunction of the dispenser electronics or alternative powersupplies, due to inadvertent simultaneous connection of the alternativepower supplies in parallel with each other, is avoided. A reliable powerlock-out functionality is provided with a simple and inexpensivemechanical arrangement.

As a further safeguard, battery compartment 95 and selected terminalsthereof may be configured to prevent connection of the batteries withthe wrong polarity. For example, terminal 101, if set to be a positiveterminal, may be inset slightly relative to adjacent flanking shoulders102 such that only the protruding positive terminal of the battery(e.g., D-size dry cell) will make contact with terminal 101. If thebattery is inserted with the wrong (reverse) orientation, the flatnegative battery terminal will abut against shoulders 102 and remainspaced from (and out of electrical contact with) terminal 101. Similarterminal arrangements may be provided at any of the other positiveterminals within battery compartment 95.

Dispenser Set-up and Dispensing Control

Upon engagement of drive mechanism 47, and the provision of power (viabattery compartment 95 or power line input port 97), dispenser 1 needonly be loaded with a roll of the sheet material to be readied for use.As with the dispenser described in application Ser. No. 09/081,637,dispenser 1 is preferably used for dispensing from a roll of webmaterial having spaced apart tearing lines, such as prescored lines ofperforation, resulting in sheet segments of a desired length, e.g., nineinches. By using a pre-perforated web material, the sheet segments canbe easily separated from the web without requiring cutting. Theperforation tensile strength can be made light enough such that the webmaterial can be easily separated along the perforation lines. By powerfeeding web 18 and providing pre-formed tear lines, the web does notneed to have sufficient strength to draw out additional portions as aleading portion is removed (as required by many known dispensers), andless pull force is required to detach a leading segment. Thus, the paperor other material of which the web is made can be better optimized forsoftness and absorbency.

When a roll 17 (see FIG. 1) is initially loaded into dispenser 1, theleading edge of web 18 may be manually fed rearward into feed nip 37formed between feed roller 33 and pressure roller 35. Preferably,however, a feed transfer mechanism (as will be described) is utilized,such that it is only necessary for the attendant to place a leading edgeportion of the web in a cradle 107 formed by face plate structure 43(see FIGS. 1 and 23). When front cover 13 is closed, a cover switch 109(see FIGS. 1 and 20) may be engaged to activate drive mechanism 47 andautomatically drive feed roller 33 in a direction (i.e.,counterclockwise as viewed in FIG. 4) to advance the web around feedroller 33 and into discharge chute 41 (see FIG. 12) formed below feedroller 33, between middle chassis member 9 and face plate structure 43.

In the event a feed transfer mechanism is utilized, closure of cover 13may also actuate the feed transfer mechanism, to press a leading edgeportion of web 18, which is draped over feed nip 37 and retained incradle 107, into feed nip 37 as feed roller 33 is driven by drivemechanism 47. The leading edge of web 18 is advanced, and ultimatelydetected by one or both of a pair of towel sensors 111, 113 (see FIGS.11–13) positioned to sense the presence of sheet material in dischargechute 41. Sensors 111 and 113 are coupled with a microprocessor 115 (seeFIG. 20) forming part of a micro-controller or the like, which isprogrammed to detect as a leading edge of dispensed web material, atransition from a web absent to a web present condition. Once a leadingedge has been detected in this manner, microprocessor 115 causes drivemechanism motor 49 to continue to run for a second interval, initializedat the point of leading edge detection, to dispense a predeterminedlength of towel. Removal of the leading sheet segment places a nextleading edge of web 18 in discharge chute 41, downstream of the feedmechanism, but upstream of sensors 111, 113. While the sensors could beany one of a variety of suitable mechanisms, for example, mechanicallimit switches or acoustical sensors, the illustrated preferredembodiment utilizes a pair of optical sensors 111, 113, each comprisingan emitter 115 and a photo-detector 117, e.g., a photo-diode orphoto-transistor (see FIG. 12). Light emitted from emitter 115 isreflected and received by associated photo-detector 117 in a certainintensity when web material is present. This intensity is reflected inthe output signals of the photo-detectors 117, which are supplied torespective input pins of microprocessor 115.

Referring to FIGS. 12 and 23, discharge chute 45 preferably defines anaccess that is narrow enough to prevent a user's fingers from reaching afree leading edge of web 18 located therein, e.g., while dispenser 1 iswaiting for a sheet request signal generated by a user proximity sensor(to be described). Sensors 111, 113 are located in discharge chute 41between discharge outlet 45 and the upstream blind end 119 (see FIG. 23)of chute 41 defined by a feed-through formed between feed roller 33 andan arcuate guide plate 121 of middle chassis member 9. With thisarrangement, towel sensors 111, 113 are substantially shielded fromambient light and potential interference caused thereby. Adverse effectscaused by ambient light can be further minimized by pulsing the emitterand high-pass filtering the output of the photo-detector, under thecontrol of microprocessor 115. In conjunction with pulsing the emitter,microprocessor 115 can be used to carry-out known synchronous detectiontechniques to further filter out any motor brush and optical noise fromthe photo-detector output, which may not be removed by the high-passfiltering. Such a technique may involve subtraction of a valuerepresentative of a photo-detector On time when the emitter is Off, froma photo-detector On time when the emitter is pulsed On. This can be donedigitally, by decrementing and incrementing a stored count value, orusing analog techniques, e.g., by charging and discharging a capacitor.

By appropriately controlling the feed of web 18, successive perforationlines 19 are located in discharge chute 41 such that each leading sheetsegment can be torn away from the remaining web 18, leaving a new freeleading edge (formerly an intact perforation line 19) slightly above thetowel sensing location of sensors 111, 113. The (new) free leading edgewill remain there until the next dispensing operation is carried out. Asmentioned, this may be upon receipt by microprocessor 145 of a sheetrequest signal generated by a user proximity sensor (to be described).Alternatively, in a “sheet hanging” mode, a sheet segment may beimmediately dispensed upon the sensing of an absence of sheet materialin the discharge chute, by sensors 111, 113. Either way, towel sensors111, 113 will register the position of the leading edge shortly afterthe feed mechanism starts feeding sheet forward, and before a secondpredetermined interval of advancement is carried out. As an alternativeto carrying out the first interval of advancement as a first step uponreceipt of a sheet request, the first interval may be carried outimmediately following removal of a sheet segment dispensed in apreceding dispense cycle. In this case, the free leading edge begins thesecond predetermined interval of advancement immediately upon receipt ofa sheet request signal, initialization of the leading edge having beenpreviously performed.

In lieu of triggering a second predetermined interval of advancement bythe direct sensing of a segment leading edge (free or otherwise), one ormore web sensors could be utilized to detect indicia (e.g., a mark orthe like) located in relation to a leading edge. In this case, detectionof the indicia by the sensor(s) would indicate arrival of the leadingedge at a first position spaced from the sensor, marking the end of thefirst interval of advancement and the beginning of the secondpredetermined interval of advancement.

As a further variation, a dispense cycle may comprise an interval ofsheet advancement and a sheet retraction interval. More specifically, afirst interval of advancement may be used to dispense a leading segmentand to place the adjacent tear line downstream of the sensor(s) a shortdistance. Once the leading segment is removed, an interval of retractionmay begin and continue until the sensor(s) detect the free leading edge(e.g., as a transition from a web present to a web absent condition).This interval of retraction serves to initialize the start of the nextinterval of advancement, to be carried out in a subsequent dispensecycle. In this embodiment, a switch or sensor separate from sensors 111,113 may be used to detect removal of the leading segment by a user, andcontrol circuitry/logic may be provided for providing alternatingforward and reverse drive cycles of feed roller drive motor 49.

Dispensed web exits discharge chute 41 through discharge outlet 45 whereit hangs externally of dispenser 1. A user may grasp the dispensed sheetsegment and pull on it, causing it to tear off along the adjacentperforation line 19 (see FIG. 1) positioned upstream of sensors 111,113. This returns sensors 111, 113 to a web absent condition. If a sheetsegment is dispensed, but the user does not remove it, sensors 111, 113will ordinarily both detect the presence of web 18. In this case,microprocessor 115 will preferably prevent further activation of motor49. Such feed inhibition serves to discourage abusive excessivedispensing, as well as to prevent potential inadvertent triggering of adispensing operation, e.g., as a result of spurious signals generated bya user detection sensor (and interpreted as a sheet request signal). Inaddition, energy savings may be realized by activating and monitoring(e.g., polling) the user detection sensor only when sensors 111, 113indicate a web absent condition. The pair of sensors 111, 113 spacedacross the width of web material 18 are advantageously utilized to causeactivation of motor 49 to carry out a dispense cycle in the event theleading towel segment is irregularly torn apart from the tearing line,uncovering only one of the two towel sensors. In lieu of a pair ofspaced sensors 111, 113, a single centrally positioned sensor may beprovided in discharge chute 41.

With reference to FIGS. 11–12, sensors 111, 113 are mounted on anelongated printed circuit board (PCB) 123 that clips into and out of aseat defined within a recess 125 of face plate structure 43. PCB 123 isretained within recess 125 by a plurality of bosses 127. Sensors 111,113 are mounted to face discharge chute 41, adjacent opposite ends ofPCB 123. Apertures are provided in the floor of recess 125 at positionscorresponding to sensors 111, 113, to provide windows through which thesensors may “look” into discharge chute 41. Signal lines (not shown)extend from sensors 111, 113 to a connector 129 attached to the end of aribbon cable 131 that extends to a main circuit board 133 (see FIGS. 2and 9).

As mentioned, microprocessor 115 preferably controls dispenser 1 to feeda sheet segment only after detecting that a previously fed sheet segmenthas been separated from the remaining web 18 (and, optionally, onlyafter receipt of a sheet request signal from a switch or sensor). Tocontrol the amount of web 18 fed so that only one sheet segment is fedper dispense cycle, and to assure a proper placement of successive tearlines in discharge chute 41, dispenser 1 employs a displacement detector135 (see FIG. 20), the output of which can be used to establish apredetermined interval of web feed during each dispensing cycle, i.e.,each time motor 49 is activated. Displacement detector 135 may be ashaft encoder, either electromechanical or optical, mounted to generatea pulse for each small increment of rotation of feed roller 33. In theillustrated exemplary embodiment, an optical shaft encoder comprises aslotted wheel 137 mounted on an axle 139 of feed roller 33, in overlyingrelationship with main PCB 133 retained within left side chassis member7. A sensor (emitter-photo-detector pair) of the encoder may be mountedon PCB 133 so as to output a pulse train corresponding to rotation ofthe wheel slots past the sensor. An alternative to encoding successiveincremental displacements of feed roller 33 is to detect the differencein transmissivity of web 18 when a perforation line 19 crosses anoptical interrupter. That is, an emitter-photo-detector combination maybe used to provide a signal that indicates a first level of lightreception as web is fed, and a second level when a perforation linecrosses the light path. A pulse may be generated by the presence of theperforations.

Microprocessor 115 preferably will count the pulses generated by sheetdisplacement detector 135 starting from the point at which a leadingedge is detected by microprocessor 115 (e.g., as transition from a webabsent to a web present condition). Dispenser 1 may be set to dispensefrom rolls with sheet segments of various length. For instance, withperforated tear lines spaced nine inches apart, microprocessor 115counts the corresponding number of pulses to dispense nine inches of web18. A switch, dial, button or other means may be provided to adjust thedisplacement per dispensing cycle to accommodate rolls having differentsegment lengths, and/or to cause dispensing of multiple sheet segments,if desired. Although, other counting arrangements, or a time baseddispense cycle, could be used for controlling the dispense interval,calculation of sheet displacement from a detected leading edge ispreferred to avoid cumulative error, i.e., error accumulated over aseries of consecutive dispense cycles. Such cumulative error couldresult in misplacement of a tear line for a leading segment, eitherdownstream of sensors 111, 113, or upstream of blind end 119 (see FIG.23) of discharge chute 41, thus resulting in a system fault condition.

“Overshoot” may occur following an On-interval of motor 49, due toinertia of the feed mechanism. To avoid this potential problem,conventional circuitry/logic can be provided to directly short the powerterminals of the motor at the end of each operation interval, to therebyprovide a known dynamic braking effect.

As a further protective measure, microprocessor 115 may be programmed tocompensate for any overshoot that does occur, by subtracting from thedesired displacement amount a predicted or anticipated overshoot amount.An appropriate value may be obtained from historical data representativeof overshoot amounts measured as the number of encoder pulses occurringafter power-down of the motor, e.g., a moving average value. Forexample, a memory may store, for a predetermined number of recentdispense cycles, a moving average of the number of counts ofdisplacement detector 135 occurring after power-down of motor 49. As afurther example, an updated running average value may be maintained by arecursive calculation averaging a most recent overshoot count value witha preceding average value (which itself was calculated by averaging thepenultimate count value with a preceding count value, etc.) The runningcalculation may be initiated upon power-up of the dispenser or closureof cover 13, and may continue until operation of the dispenser isinterrupted, e.g., by opening of the cover or battery depletion. Astarting “average” value (for use in the initial dispense cycle) may bechosen based upon empirical data.

Accommodation of “Tabbing” With reference now to FIG. 13, it isexplained how the web sensing system of dispenser 1 may handle variouspossible scenarios in which tearing occurs other than strictly alongtear line 19. Broken lines 141 and 143 both depict internal “tabbing”tears, that is, tears that result in an irregular tab of web material 18remaining wholly within discharge chute 41, upstream of sensors 111,113. Broken line 145 depicts an external “tabbing” tear, wherein anirregular tab of web material extends over at least one of sensors 111,113 (and generally outside of discharge chute 41). Through utilizationof two spaced sensors 111, 113, and as has been described, removal of aleading segment can be detected notwithstanding this external tabbingcondition, by sensing the absence of web material at either one of thetwo sensors.

Tear line 141 may be said to result in downstream internal tabbing, inthe sense that the irregular tab that results is downstream of tear line19 (yet still upstream of sensors 111, 113). Tear line 143 may be saidto result in upstream internal tabbing, in the sense that the irregulartab that results is upstream of tear line 19. With a single centrallylocated web sensor, these two scenarios would not cause a problem, asthe sensor would be positioned to detect the tear along tear line 19 asthe leading edge, and initialize further feed from that point. On theother hand, these conditions may cause a problem when a pair of spacedsensors, such as sensors 111, 113, are utilized, in that detection of aleading edge will occur along the irregular tear line 141 or 143downstream or upstream of tear line 19, with the result that theinitialization of sheet feed occurs either upstream or downstream oftear line 119; such improper initialization would result in successivemisplacement of subsequent tear lines.

A “first edge detection” system may be employed to avoid a dispenserfault condition arising as a result of upstream internal tabbing. Inthis system, microprocessor 115 initializes a second interval ofadvancement based upon the first edge detected by sensors 111, 113, onthe assumption that the first detected edge is an edge formed along tearline 19. Tabbing that occurs downstream of tear line 19 is generally ofthe “external” kind illustrated with line 145, leaving a tab whichextends externally of discharge chute 41, or at least downstream of oneof sensors 111, 113, such that the sensor at the tabbed side continuesto detect the presence of web material. In this instance, and as hasbeen described, the uncovering of at least one of sensors 111, 113(sensor 113 as illustrated in FIG. 13) signals removal of a leadingsegment of sheet material, satisfying a web absent condition formicroprocessor 115 to initiate a dispense cycle. Upon initiation of adispense cycle, initialization of the dispense counter (for starting thesecond interval of advancement) occurs upon the same sensor detecting aleading edge.

In accordance with one of the present inventions, microprocessor 115 maybe programmed to avoid the above-mentioned initialization problem thatmay arise as a result of the internal tabbing scenarios depicted by tearlines 141 and 143. A memory may store a nominal measure of the firstinterval of sheet advancement. This may be a constant value, e.g., setto correspond to one half the distance between the blind upstream end119 of discharge chute 41 (see FIG. 23) and sensors 111, 113.Alternatively, the memory may store, for a predetermined number ofrecent dispense cycles, a moving average of the number of counts ofdisplacement detector 135 occurring from activation up to the point thata leading edge is detected (the first variable interval of advancement).The moving average may be computed by other known techniques, such asrecursively in the manner previously described in connection withprediction of a feed mechanism overshoot amount. The nominal value(e.g., a set value or a moving average value) may then be comparedagainst the count corresponding to a first edge detection by one ofsensors 111, 113. If the latter count differs significantly from thenominal value, then it may be concluded that the detected edge is a badedge, i.e., one not along tear line 19, in which case microprocessor maysimilarly validity check the count corresponding to a second edgedetection by the other sensor. If the comparison shows that detection tobe valid, then initialization may be properly carried out from thatpoint. If neither sensor sees a good edge, then initialization of thedispense cycle may be carried out at a point corresponding to the storednominal value. In this manner, successive placements of tear lines 19may be properly maintained within discharge chute 41, upstream ofsensors 111, 113, thereby avoiding a dispenser fault condition.

If a user pulls on the leading edge of the sheet segment being dispensedbefore the cycle has been completed, motor 49 may stall due to theincreased load placed on worm gear 51. (As mentioned, worm gear 51cannot be reverse driven by spur gear 57; thus, a user pull will notcause motor 49 to accelerate.) Web 18 generally will be prevented fromslipping about feed roller 33 when pulled because of the pinchingengagement of feed nip 37. When the motor stalls, microprocessor 115 maystore the cumulative displacement (to the point of the stall) andreactivate motor 49 to dispense the remaining portion of the sheetsegment after a short pause. Alternatively, motor 49 may be reversed sothat the sheet segment is pulled upstream of towel sensors 111, 113 andfed forward again to register the leading edge again in preparation fora new dispensing cycle.

Dispenser Feed Transfer Mechanism

As previously mentioned, web 18 may be introduced into the feedmechanism by a transfer mechanism. With reference to FIGS. 1, 2, 4, 9and 14–15, the transfer mechanism may include a transfer bar 147pivotally mounted between side chassis members 5, 7 and a transfer drivesystem 149 for driving transfer bar 147 by way of an electric transfermotor 151 located within left side chassis member 7. Transfer drivesystem 149 utilizes a series of linkages to convert rotation of theoutput shaft of transfer motor 151 to pivotal movement of transfer bar147, and fingers 153 thereof, in the direction of feed nip 37, toposition a leading portion of web 18 in nip 37 while feed roller drivemotor 49 is being operated. Similar to drive motor 49, transfer motor151 preferably has low DC power requirements and is powered by batteriesloaded in compartment 95, or by a line/plug connected to power lineinput port 97. Obviously, a separate power supply for motor 151 couldinstead be provided.

Under the control of microprocessor 115, transfer motor 151 ispreferably activated in response to a determination being made eitherthat a working roll is not present, or that one that is present iscompletely depleted. Such a determination may be made using sensors 111,113 to detect the presence or absence of web 18 within discharge chute41. If a web absent condition is detected and sustained for apredetermined operation interval of drive motor 49, this is indicativeof the working roll being depleted, or the absence of one in thedispenser. Under this condition, transfer motor 151 is activated tocarry out a first transfer attempt. If the first transfer attempt doesnot result in detection by sensors 111, 113 of web material in dischargechute 41, a second transfer attempt is preferably carried out. If, afterthe second transfer attempt, web material is still not detected, it maybe assumed that a reserve roll (to which feed would ordinarily betransferred) is not present in upper roll support hubs 21, 27.Accordingly, an alarm or indicator, such as a flashing LED 154 (seeFIG. 1) may be activated to alert the attendant to the need to replenishthe dispenser with roll material.

To facilitate maintenance of a reserve roll in dispenser 1, a sensor canbe provided to detect when a working roll held in the upper pair ofsupports 21, 27 has been depleted sufficiently for it to be moved tolower pair of supports 29, 31. In one embodiment, and as shown in FIG.1, this sensor is provided in the form of a pivotal arm 155 lightlyspring-biased against the outer circumference of the roll placed in theupper pair of support hubs 21, 27. Arm 155 may have a pivotal attachment157 to back panel member 11, and be positioned to actuate a switch thatchanges state (e.g., closes) when the diameter of the roll is reduced toa certain extent, to activate LED indicator 154. The switch may, e.g.,be incorporated into left side chassis member 7. Alternatively, inaccordance with one of the present inventions, program logic can be usedin conjunction with microprocessor 115 to determine when the roll hasbeen depleted sufficiently for it to be transferred to lower pair ofsupports 29, 31. For example, the amount of roll depletion may bedetermined by subtracting a cumulative dispense amount (e.g., calculatedfrom the output of displacement detector 135) from a stored initialnominal roll length. LED indicator 154 may be activated upon thecalculated roll depletion reaching or exceeding a stored target transfervalue.

As best seen in FIG. 14, transfer bar 147 is an elongated member havinga plurality of cross braces that provide extra rigidity. Transfer bar147 is pivotally connected to side chassis members 5, 7 and extendsbetween those members along the length of feed nip 37. Transfer bar 147also includes cover engaging members 157 having rounded upper shoulders159 that will slide smoothly along the inside of front cover 13, ascover 13 is closed. Ultimately, engaging members 157 will rest againstthe inside of a front panel of cover 13 to place transfer bar 147 in theset, transfer ready position depicted in FIG. 15.

A pair of sleeve bearings formed at opposite sides of face platestructure 43 pivotally support respective stub shafts 161 protrudingoutwardly from opposite ends of transfer bar 147. This pivotal mountpermits transfer bar 147 to rotate (counterclockwise in FIG. 15) whencover 13 is pivoted to an open position. In this manner, transfer bar147 and cover 13 can both rotate to respective web loading positions,e.g., as shown in FIGS. 1 and 4, in which they are conveniently out ofthe way of the attendant loading the dispenser. The pivotal mount alsopermits transfer bar 147 to rotate about shafts 161 in the direction ofnip 37 (clockwise in FIG. 15) when the transfer drive mechanism isactivated, as discussed below.

Rigid transfer fingers 153 are placed along the length of transfer bar147 for engaging web 18 and positioning it in the nip 37 formed by feedroller 33 and pressure roller 35. The number of transfer fingers 153 canbe varied depending on the length of the transfer bar and/or thestrength of the web to be dispensed. With a relatively weak webmaterial, a closer spacing of the transfer fingers can be used to reducestress concentrations at the transfer finger contact points, so as toavoid web perforation or tearing. As shown, e.g., in FIG. 15, fingers153 extend away from the transfer bar in the direction of nip 37. Thesefingers 153 include rounded web contacting ends that are directed at nip37 when transfer bar 147 is in its set position. The forward edge ofeach finger 153 is rounded and sized so that it will engage and positionweb 18 between the rollers 33, 35 without tearing or perforating theweb, when transfer bar 147 is advanced from the set position to the webtransfer position.

Referring to FIGS. 14–15, the transfer drive system includes an outputgear 163 which is connected to the output shaft of transfer motor 151,and a transfer gear 165 that meshes with output gear 163 so thattransfer gear 165 will rotate when transfer motor 151 is operated.Transfer gear 165 forms an arc sector of a circle. A plurality of gearteeth are formed along the outer circumference of transfer gear 165.These teeth mesh with the teeth of output gear 163. Output gear 163drives transfer gear 165 in a clockwise direction (as shown in FIG. 15)when transfer motor 151 is operated. Transfer gear 165 rotates about anaxis 167 that is located at the center of the circle from which the arcsector of transfer gear 165 is taken.

A rigid transfer link 169 extends between transfer gear 165 and transferbar 147 for imparting movement to transfer bar 147 in relation to therotation of transfer gear 165. Transfer link 169 is, at a first end 171,rotatably mounted on an enlarged inwardly directed hub portion 173 oftransfer gear 165, by a linkage plate 175. Hub portion 173 iseccentrically located relative to transfer gear rotation axis 167, asbest seen in FIG. 15. As transfer gear 165 is driven in a clockwisedirection by output gear 163, as shown in FIG. 15, linkage plate 175 isdisplaced slightly upwardly and then rearwardly, following thecorresponding translation of eccentric hub 173. Due to the freelyrotatable mount of linkage plate 175 on hub 173, the clockwise rotationof hub 175 is not transmitted to transfer link 169. The first end 171 oftransfer link 169 rises and moves rearwardly with the translatorymovement of linkage plate 175.

At a second end 177, transfer link 169 includes an open bottom hook 179that engages a post 181 extending outwardly from one side of transferbar 147 in the direction of one of left side chassis member 7, in spacedrelation to the pivot axis of transfer bar 147. As first end 171 oftransfer link 169 moves with linkage plate 175 in response to rotationof transfer gear 165, hook 179 remains engaged with post 181 and causesit to be pulled rearwardly, as transfer link 169 both rotates andtranslates. As a result, transfer bar 147 is rotated about its pivotaxis and fingers 153 begin to move toward nip 37. With continuedrotation of transfer gear 165, transfer bar 147 is positionedimmediately in front of nip 37 so that transfer fingers 153 contact web18 and position it within nip 37. A resistance to further rotation oftransfer gear 165, resulting from a pressing contact of fingers 153against one or both of feed roller 33 and pressure roller 35, orresulting from a stop member 183 suitably placed on a backside oftransfer gear 165 abutting with a suitably placed stop structure 185 ofleft side chassis member 7, can be used to trigger a deactivation oftransfer motor 151 by known means. For example, a high currentassociated with a stall condition of motor 151 can be sensed byappropriate circuitry provided on main PCB 133 (see FIGS. 2 and 9) andused to deactivate motor 151.

As seen in FIGS. 14–15, the bottom of hook 179 is open and the front,inner edge 187 of hook 179 is beveled so that post 181 can move in andout of hook 179 depending on the positions of front cover 13. Edge 187forms at its top a peak 189 for engaging post 181 and urging it into aseat 191 formed there above when transfer link 169 moves toward the rearof dispenser 1 in response to rotation of transfer gear 165. When cover13 is opened, post 181 falls out of hook 179 through the open bottom andtransfer bar 147 rotates downwardly, as discussed below. As cover 13 isclosed, post 181 moves into the open, lower side of hook 179 by passingalong beveled edge 187. The inner, open area of hook 179 is larger thanthe diameter of post 181 so that post 181 has adequate clearance to dropout of hook 179 and away from transfer link 169 when cover 13 is opened,and to return into hook 179 as cover 13 is closed. The rearward insideof hook 179 includes a recessed portion forming a seat 193 for receivingpost 181 and returning it with transfer bar 147 to its set position.

The transfer mechanism also preferably includes a return mechanism forreturning transfer bar 147 to its set position. In a preferredembodiment, this mechanism comprises a spring retaining member 195 whichsecures a first end of a coil spring 197, or other type of resilientreturn member, to transfer gear 165. The second end of coil spring 197is suitably secured to left chassis member 7 or another part ofdispenser 1. When transfer bar 147 is in its set position, coil spring197 is relaxed or just lightly tensioned. When transfer gear 165 rotatesin response to operation of transfer motor 151 and rotation of gear 163,coil spring 197 is extended, transfer link 169 is caused to move towardthe rear of the dispenser and transfer bar 147 rotates in the directionof nip 37. After transfer gear 165 has rotated to its limit (thuscausing a leading edge portion of web 18 to be transferred into nip 37),transfer motor 151 is deactivated. The output shaft of deactivatedtransfer motor 151 free-wheels in its reverse direction, allowing spring197 to return to its rest state while returning transfer gear 165 to itsset position (the same position it was in before transfer motor 151 wasactivated). During the return stroke, seat 193 engages post 181 andreturns it and transfer bar 147 to their set positions. Instead of aspring-biased return mechanism, the motor control circuitry couldprovide a reverse drive of transfer motor 151 serving to drive transferbar 147, transfer link 169 and transfer gear 165 to their set positionsafter web 18 has been introduced and fed through nip 37.

To load a roll in dispenser 1, or to transfer a partially depleted rollfrom upper supports 21, 27 to lower supports 29, 31, an attendantunlocks or unlatches dispenser cover 13 and rotates it downwardly to theweb loading position shown in FIG. 1. In its open position, the frontpanel of cover 13 will no longer abut against transfer bar 147 andsupport it in its set position. As a result, transfer bar 147 will fallout of hook 179. Transfer bar 147 pivots downwardly away from nip 37about stub shafts 161 as has been described. Both cover 13 and transferbar 147 assume respective web loading positions where they will notinterfere with an attendant installing a roll in the dispenser 1 andpositioning a leading edge portion of web 18 for transfer into feed nip37.

In a preferred embodiment, upon loading a reserve roll into upper pairof supports 21, 27, the attendant will position the leading edge portionof web 18 in cradle 107 located in front of, and below, feed nip 37.After positioning web 18 in cradle 107, the attendant will close cover13 by rotating it upward toward the chassis assembly and back panelmember 11. As the cover is rotated upwardly, an inner front surface ofcover 13 contacts cover engaging members 159 on transfer bar 147 androtates transfer bar 147 to its set position, as has been described. Ascover 13 is being closed and transfer bar 14 is rotated to its setposition, post 181 is pivoted upwardly into hook 179.

As cover 13 is closed, cover switch 109 (see FIGS. 1 and 20) is engagedto activate feed roller drive motor 49, to advance any sheet materialpresent in the feed mechanism. Concurrently, sensors 111, 113 detect thepresence or absence of web 18 in discharge chute 12. When an absence ofweb continues to be detected by sensors 111, 113 for a predeterminedadvancement interval, the feed transfer mechanism is actuated, as feedroller 33 continues to be driven. With reference again to FIG. 15,transfer motor 151 drives output gear 163 in a counter-clockwisedirection, which in turn drives transfer gear 165 in a clockwisedirection. This results in transfer link 169 moving rearwardly. Astransfer link 169 moves rearwardly, hook 179 engages post 181 andimparts the movement of link 169 thereto. As post 181 is pulledrearwardly, transfer bar 147 pivots toward feed nip 37 about stub shafts161. Fingers 153 engage the leading portion of web 18 hanging in frontof nip 37. Fingers 153 rotate until they abut against, or reside inclose proximity to, feed roller 33 and/or pressure roller 35. As thisoccurs, web 18 is introduced into nip 37 and taken up by the feedmechanism, and transfer motor 151 is deactivated. Once motor 151 stops,return spring 197 (or another return mechanism) causes transfer link 169and transfer bar 147 to return to their set positions.

After a transfer of feed to a reserve roll rotatably supported betweenupper supports 21, 27, dispensing from that roll (now the working roll)may continue until the web sensing system detects that that roll hasbeen fully depleted. (As previously described, a sensor may, in theinterim, signal a partial depletion condition permitting transfer of theroll from upper supports 21, 27 to lower supports 29, 31.) Whendepletion of the working roll is sensed, e.g., by the continued absenceof web material at the sensing position following advancement of thefeed roller a predetermined amount, the transfer mechanism is activatedfor introduction of a leading portion of the reserve roll material intothe feed nip. This introduction is accomplished in the manner discussedpreviously with respect to the introduction and feeding of an initialroll loaded into the dispenser following closure of cover 13. Incarrying out an automatic feed transfer, fingers 153 position thereserve web in nip 37 without cover 13 being opened, so that the reserveweb is introduced into, and picked up by, the feed mechanism immediatelyfollowing depletion of the prior roll. The feed transfer operation maythus be carried out in a manner that is substantially transparent to theuser.

Electrically Actuated Release of Spring Biased Transfer Bar

An alternative arrangement for effecting a transfer of feed to a new orreserve roll is now described with reference to FIGS. 16A–16E. In thisembodiment, an electrically actuated device, e.g., a motor 199, isutilized to actuate release of a transfer bar 200, which is biasedtoward feed nip 371 by a spring 201, or the like.

Referring to FIG. 16A, a dispenser 1′ is shown in a condition where webmaterial 203 has been fed from a stub roll 204 through a feed mechanismformed by a feed roller 33′, a pinch roller 35′, a middle chassis member9′ and a face plate structure 43′. A reserve roll mounted in an upperpair of supports (not shown) has a leading portion of sheet material 18′hanging down in front of a feed nip 37′. Pivotally mounted transfer bar200 is spring loaded rearwardly by spring 201, which is braced againstan inside front surface of closed cover 13′. Transfer bar 200 is held ina set position by a pivotally mounted transfer link 205. Transfer link205 is biased to its most counter-clockwise position by a tension spring207. The pivotal motion of transfer link 205 is limited in bothdirections by pins 209, 211. When the web 203 from stub roll 207 iscompletely depleted, the dispenser control system senses this (in amanner as has been described), and power is applied to transfer motor199.

Referring to FIG. 16B, dispenser 1′ is shown after stub roll 204 hasbeen completely depleted and transfer motor 199 has been activated torotate transfer link 205 clockwise, overcoming the pull of spring 207.This rotation of transfer link 205 frees transfer bar 200 to rotatecounter-clockwise under the bias of spring 201, pushing the leadingportion of web 18′ into feed nip 37′.

In FIG. 16C, dispenser 1′ is shown just after a feed transfer has beencompleted. The leading sheet segment has been fed through nip 37′ andhas emerged from discharge chute 41′ and outlet 45′ in a folded-overstate. Transfer motor 199 is turned off once transfer link 205 has beenpivoted to its limit. This can be effected by having the dispenserelectronics detect a stall condition as transfer link 205 bottoms ontravel limiting pin 209. Once motor 199 is switched off, transfer link207 is permitted to relax into its counter-clockwise position againstpin 211, under the bias of spring 207. In place of motor 199, anelectric solenoid or the like may be suitably arranged to move transferlink 205 to its transfer bar setting and/or release positions.

Referring now to FIG. 16D, dispenser 1′ is shown with dispenser cover13′ open so that it may be refilled. Having cover 13′ open allowstransfer bar 200 to fall open (pivot forwardly) by virtue of itsover-center position. Empty stub roll core 204 has been released to fallthrough a gap 213 formed between middle chassis member 9′ and back panelmember 11′ into cover 13′ where it can be easily removed by theattendant. The roll of paper held in the upper supports (not shown),from which web 18′ extends, has been depleted to the point that it maybe transferred from the upper pair of supports to the lower position, asillustrated in FIG. 16E, while web 18′ remains fed through the feedmechanism.

FIG. 16E shows dispenser 1′ in a reload condition. Working roll 17′ hasbeen moved to the lower stub roll position while web 18′ remains fedthrough the feed mechanism. A new full roll (not shown) has been placedin the upper supports and a leading segment 18″ drapes down over feednip 37′. The web can be placed in a clip or cradle, as has beendescribed, or transfer bar 200 itself may serve to hold the web. Uponclosing cover 13′, transfer bar spring 201 is loaded and dispenser 1′assumes once again the condition shown in FIG. 16A.

Roll Core Removal

Referring now to FIGS. 1, 4, 9, 17 and 18, a system permitting highlyefficient removal of spent stub rolls (roll cores) from dispenser 1 isdescribed. Lower roll support 29 connected to right side chassis member5, together with opposing support hub 31 connected to left side chassismember 7, provide a releasable rotatable mount for a web material rolltransferred down from upper supports 21, 27. So mounted, a transferred“stub” roll, from which material may continue to be fed, is positionedin alignment with an elongated, generally rectangular gap 215 (see FIG.17) defined between dispenser back panel member 11 and middle chassismember 9. Support 29 is made movable by finger operation between a coreretention position and a core release position. Displacement of support29 to its release position moves a mounting hub 217 thereof away fromopposing (fixed) support hub 31, thereby increasing the distance betweenthe opposed roll core hubs to the point where the core 219 (see FIG. 18)is no longer supported. Upon support 29 being moved to its releaseposition, retained core 219 is thus released to fall directly throughgap 215. In its open position, e.g., as seen in FIG. 9, dispenser cover13 is positioned to receive roll core 219 dropped through gap 215, andto place it where a custodian can easily remove it.

As seen clearly in FIG. 18, releasable support 29 includes a spring arm221, a finger graspable release handle 223, and roll core mounting hub217. At its upper end 225, spring arm 221 is cantilever mounted to aninner side of a wall 225 of right side chassis member 5. In its restposition, a major lower portion of spring arm 221 is angled inwardlywith respect to the inner side 225, toward roll core 219. Release handle223 and mounting hub 217 are each disposed adjacent the lower end ofspring arm 221, protruding laterally from opposite sides thereof.

Release handle 223 is provided in the form of a slightly curved tab witha built-up outer edge 227. Handle 223 extends through a passage 229formed in wall 225 such that it is readily graspable by an attendantfrom the outside of right side chassis member 5, once cover 13 isopened.

A catch arm 231 is also preferably attached to the lower end of springarm 221. Catch arm 231 extends laterally from spring arm 221, belowrelease handle 223, through a passage 232 provided chassis wall 225.Catch arm 231 has a downwardly directed catch member 233 proximate itsouter end 235. Catch member 233 and passage 229 are sized and configuredsuch that catch member 233 abuts with an outside surface of chassis wall225 to limit the inward deflection of spring arm 221 when no roll core219 is present. As such, catch member 233 serves to maintain spring arm221 in a set position, facilitating roll insertion by mere dropping ofthe roll in between support hubs 217, 31; the need for separate manualretraction of roll support 29 using release handle 223 is not requiredto load a roll.

Cover 13 is pivotally mounted at its lower rear corner to back panelmember 11, and opens by rotating away from the chassis assembly to theopen position shown, e.g., in FIG. 9. In the open position, a cavity 235formed by the cover front panel and sidewalls extends below gap 215 tocatch a core 219 released from lower supports 29, 31 and dropped throughgap 215. As best seen in FIG. 9, in the open position, the cover frontpanel forms a cavity floor 237 which is inclined slightly forwardly.This incline serves to encourage a core dropped thereon to roll, undergravitational force, into a forward portion of the open cover, where itmay be readily removed by an attendant.

Proximity Sensing System

Referring to FIG. 20, dispenser 1 preferably includes, as a sheetrequest switch/sensor 249, a proximity sensing system for detecting thepresence of a user's hands or the like as they approach the front ofdispenser 1. As generally described in application Ser. No. 09/081,637,the sensor may be of any suitable type, and preferably is a non-contactsensor such as a capacitive or IR sensor. In the illustrated preferredembodiment, a proximity sensor antenna plate 239 (see, e.g., FIGS.11–12) is driven by an oscillator circuit. The oscillator circuit iscoupled with microprocessor 115, which detects the presence of a user'shand based upon a voltage related to the amplitude of the oscillations.Microprocessor 115 activates motor 49 when a hand is detected, so as todrive feed roller 33 and thereby dispense a length of the material.

As best seen in FIGS. 11–12, antenna plate 239 may be formed as ametalized front-facing surface of an elongated printed circuit board(PCB) 241 that may be clipped into place on faceplate structure 43, inoverlying relation with PCB 123. This may be accomplished with adeflectable spring arm 243 located on faceplate structure 43, to theright side of recess 125, and a pair of shoulder-forming bosses 245, 247positioned one above the other at a left side of recess 125.

FIG. 19 shows a schematic diagram of a preferred embodiment of aproximity sensing system 249 that is used for sensing the proximity ofuser's hand as the user's hand approaches the front of the dispenser 10.Proximity sensing system 249 includes an oscillator circuit 251 and anautomatic sensitivity control circuit 253. Oscillator circuit 251includes an inductor L1, capacitors C15, C16 and C17, npn transistorsQ16 and Q14, and resistors R35 and R17 that are connected in a Colpittsoscillator-type topology, that is, having a split capacitorconfiguration (capacitors C16 and C17). Automatic sensitivity controlcircuit 253 includes transistors Q12, Q5 and Q15.

In oscillator circuit 251, the base of transistor Q16 is connected toone terminal of inductor L1 and to one terminal of capacitor C17. Theother terminal of capacitor C17 is connected to one terminal ofcapacitor C16. The other terminal of capacitor C16 is connected to theremaining terminal of inductor L1. Antenna plate 239 is connected to thebase of transistor Q16 at the point in the resonant circuit formed byinductor L1 and capacitors C16 and C17 that is normally connected toground. A shield 255 is physically positioned between antenna plate 239and optical sensors 115, 117, and is connected to the junction ofcapacitors C16 and C17. The collector of transistor Q14 is connected tothe emitter of transistor Q16 and to the junction of capacitors C16 andC17. The base of transistor Q14 is connected to the emitter oftransistor Q16 through resistor R35, and to ground through capacitorC15. The emitter of transistor Q14 is connected to an automaticsensitivity control circuit formed by transistors Q12, Q5 and Q15, andwhich will be described below.

As shown in FIG. 19, transistors Q16 and Q14 are each preferablyMMBT3904 npn transistors. Preferably, inductor L1 is a 330 μH inductor,capacitor C16 is a 1500 pF capacitor, capacitor C17 is an 1800 pFcapacitor, and capacitor C15 is an 0.01 μF capacitor. Preferably,resistor R35 is a 100 kΩ resistor. The collector of transistor Q16 isconnected to a suitable power supply voltage, such as +5 Vdc, and thebase of transistor Q16 is connected to a drive voltage signal PROX_ENthat is output from microprocessor 115 through resistor R37. ResistorR37 is preferably 332 kΩ. Test point T6 is connected to signal PROX_ENfor convenience in troubleshooting. When drive voltage signal PROX_EN islow, oscillator circuit 251 is disabled. When drive voltage signalPROX_EN is high, oscillator circuit 251 is enabled.

Transistor Q16 is the active element of oscillator circuit 2000, andtransistor Q14 is an active load for transistor Q16. Transistor Q14allows the necessary current to flow through transistor Q16, while notloading down the output of transistor Q16. Transistor Q14 alsostabilizes the amplitude of the oscillator output by adjusting thecurrent through transistor Q16. In the absence of oscillation,transistor Q14 is biased fully on by resistor R35, allowing maximumcurrent to flow through transistor Q16. Transistor Q16 receives basedrive through resistor R37. The transistor noise that starts oscillationis coupled to ground through antenna plate 239. There is alwayssufficient stray capacitance through the sensor field to antenna plate239 for oscillation to occur, even when no hand is in the sensing fieldof antenna plate 239.

In the illustrated preferred arrangement of antenna plate 239 andoptical sensors 115, 117, the optical sensors contribute a straycapacitance that is approximately two orders of magnitude greater thatthe stray capacitance of a hand. That is, the stray capacitance betweenantennal plate 239 and optical sensors is about 100 pF and the straycapacitance of a hand is about 1 pF. In the illustrated preferredarrangement of the invention, oscillator circuit 249 drives shield 255(see FIGS. 12 and 19), which is formed as a metalized layer on aback-side of PCB 241 (which has antenna plate 239 formed on its frontsurface). This reduces the baseline stray capacitance of antenna plate239, and minimizes the stray capacitance to antenna plate 239 caused byoptical sensors 115, 117, thereby improving sensitivity for detectingthe presence of a hand near antenna plate 239.

As depicted in FIG. 22, a relatively large ground plate 257 ispreferably mounted on the bottom surface of middle chassis member 9.Ground plate 257 may be provided, e.g., in the form of an adhesivelyapplied metal foil/plastic laminate. Ground plate 257 serves to directdownwardly and render more predictable the sensing field generated bythe oscillation applied to antenna plate 239, as the signal naturallyseeks the most direct path to ground.

Once oscillation begins, the base-to-collector junction of transistorQ14 becomes forward biased, draining some charge off capacitor C15, andcausing transistor Q14 to reduce the current drawn through transistorQ16 in order to maintain a fixed oscillation amplitude. The positivepeak of oscillation at the emitter of transistor Q16 is approximatelyVcc (+5 Vdc), while the negative peak is approximately the voltage oncapacitor C15 minus about 0.6 V. The voltage on capacitor C15 is heldconstant because the emitter voltage of transistor Q14 is held constantby the automatic sensitivity control circuit formed by transistors Q12,Q5 and Q15.

When a hand is placed near antenna plate 239, the stray capacitance ofantenna plate 239 increases from a baseline stray capacitance of antennaplate 239 caused the dispenser components and the ambient environment inwhich dispenser is positioned. As the stray capacitance increases, thepath that the sensing field must travel in order to return to ground isshortened, and the oscillator tries to oscillate at an increasedamplitude. The increased oscillation amplitude drains off additionalcharge from capacitor C15, reducing the current through transistor Q16,and thereby counteracting the increased amplitude of oscillation. Thechange in current is sensed across resistors R33 and R36 and isamplified by Q12 and Q5 to a usable level and sent to an analog input ofmicroprocessor 115 as a V_PROX_OUT signal, where it is used to trigger adispensing operation. The sudden drop in voltage at the collector of Q5is interference filtered and detected by firmware and, if considered avalid trigger event, starts the dispenser. Test point T1 is connected tosignal V_PROX_OUT for convenience in troubleshooting.

Automatic sensitivity control circuit 253 includes transistors Q12, Q5,Q15 and Q6, resistors R18, R21, R22, R25, R26, R31, R33 and R36, diodeD8 and capacitors C10 and C12. The base of transistor Q12 is connectedto the emitter of transistor Q14. The collector of transistor Q12 isconnected to the power supply voltage through resistor R21 and to thebase of transistor Q5. The emitter of transistor Q5 is connected to thepower supply voltage, and the collector of transistor Q5 is connected tothe emitter of transistor Q12 through resistor R25, to the anode ofdiode D8, and to one terminal of capacitor C10. The cathode of diode D8is connected to the gate of transistor Q15 and to one terminal ofcapacitor C12. The drain of transistor Q15 is connected to the emitterof transistor Q14 through resistor R33 and to ground through resistorR36. The collector of transistor Q6 is connected to the gate oftransistor Q16 through resistor R22. The emitter of transistor Q6 isconnected to ground, and the base of transistor Q6 is connected to aPROX_SH signal that is output from microprocessor 115.

As shown in FIG. 19, transistors Q12 and Q6 are each preferably MMBT3905npn transistors, transistor Q5 is preferably an MMBT3906 pnp transistor,transistor Q15 is preferably an MMBF170 MOSFET. Preferably, theresistance values of resistor R18 is 221 kΩ, R21 is 100 kΩ, resistor R22is 475 kΩ, resistor R25 is 22.1 kΩ, resistor R26 is 100 Ω, resistor R31is 499 Ω, resistor R33 is 332 Ω and resistor R36 is 4.75 kΩ. Preferably,diode D8 is a DL4148 diode, and preferably capacitor C10 is an 0.01 μFcapacitor. Capacitor C12 is preferably a 10 μF capacitor.

The automatic sensitivity control circuitry formed by transistors Q12,Q5 and Q15 compensates for the reduction in sensitivity for sensing ahand when more stray capacitance is added to the dispenser's senseenvironment, that is, when the baseline stray capacitance of antennaplate 239 is relatively large because, e.g., a large metal object islocated near antenna plate 239. The reduction in sensitivity for sensinga hand in an environment providing a relatively larger baseline straycapacitance is due to the fact that the change in capacitance due to ahand in the sensing field is a relatively smaller percentage of theoverall capacitance sensed by antenna plate 239.

In operation, the automatic sensitivity control circuitry maintainsapproximately 3 V at the collector of transistor Q5 and approximately0.6 V at the emitter of transistor Q14. When, e.g., a large metal objectis brought near dispenser 10, transistor Q14 will reduce the currentflow through transistor Q16, thereby correcting an increase in theoscillation amplitude caused by the increased stray capacitance sensedby antenna plate 239. The reduction in current through transistor Q16lowers the voltage on the emitter of transistor Q14. The voltage at thecollector of transistor Q5 begins to decrease due to the gain oftransistors Q12 and Q5 (as set by resistors R31 and R25). As a result,capacitor C12 discharges through its own leakage or through resistor R22(depending on firmware mode) and causes transistor Q15 to conduct less.Because transistor Q15 is a MOSFET, the resistance of transistor Q15increases, thereby increasing the resistance between the emitter oftransistor Q14 and ground and effectively increasing the proximitydetection circuit gain, while lowering the oscillator current by ancorresponding amount. Resistors R33 and R36 limit the adjustment rangeof the control loop in order to keep the automatic sensitivity controlloop stable. Transistor Q6 and resistor R22 function as an AGC pull-downcircuit for speeding recalibration of proximity sensor circuit 251 undercontrol of microprocessor 115 through the PROX_SH signal. Test point T14is connected to signal PROX_SH for convenience in troubleshooting.

When a hand is removed from the sensing field, readjustment of thecontrol loop for maximum sensitivity occurs rapidly due to diode D8.Reduction of proximity sensitivity, such as when a hand is in thesensing field, is much slower and is determined by the leakage incapacitor C12 and whether transistor Q6 is turned on.

While proximity sensor system 249 has been described in the context ofsheet material dispenser 1, it should be understood that the proximitysensor system of the present invention can be used in virtually anyapplication where it is desired to detect the presence or proximity of auser, or other object, relative to something else. This includes (but isnot limited to) various types of hands-free or automatic dispenserdevices, such as water faucets or fountains, soap dispensers and drinkdispensers.

Additional Electrical System/Control Aspects

The various electrical components of dispenser 1, and theirinterrelationship with each other, are shown in the block diagram ofFIG. 20. In addition to receiving input signals from proximity sensingsystem 249, optical sensors 111, 113, sheet displacement detector(encoder) 135, and cover switch 109, microprocessor 115 may alsooptionally receive input from a manual reset button 259 effectivelyserving to return the state of microprocessor 115 to the initial stateassumed upon closure of cover 13. In addition, microprocessor 115 may beused to pulse power on and off to optical sensors 111, 113, and todisplacement detector 135, as an energy saving measure. As a furtherenergy saving measure, program logic (e.g., a watch-dog timer) may beprovided to place microprocessor 115 in a sleep mode after apredetermined period of inactivity, and to periodically wake the systemfrom the sleep mode. In a preferred embodiment, proximity sensing system249 is powered down, and not polled, so long as optical sensors 111, 113indicate the presence of web material in discharge chute 19.

Microprocessor 115 and/or associated circuitry preferably comprise avoltage detector for detecting a low battery condition of the dispenserand indicating the same, e.g., by flashing a low battery indicator LED260 (see FIGS. 1 and 20). Microprocessor 115 may also be used inconjunction with the voltage detector to provide pulse width modulation(PWM) control of drive motor 49 and/or transfer motor 151, in order tomaintain a substantially constant motor speed despite fluctuations inthe output voltage of the batteries over their lifetime. In this manner,a desirable consistency of dispense (and transfer) cycle times can beachieved; in addition, potential for the previously described feedmechanism overshoot problem can be reduced.

An option switch may be provided for switching dispenser 1 to a “towelhanging” mode. Upon closure of cover 13, microprocessor 115 may checkthe option switch and if set to the “towel hanging” mode, the proximitysensing system may be disabled entirely until the next system reset(such as by a subsequent cover closure, or actuation of reset switch259). In this mode, optical sensors 111, 113 may be polled at a reducedrate (e.g., two times per second) to cause a dispensing operation to becarried out upon the detection of a web absent condition. Alternatively,optical sensors 111, 113 may be powered down and not polled until aftermicroprocessor 115 is awakened by an interrupt generated by theproximity sensing system detecting a hand in close proximity to thedispenser (a sheet request). Instead of waking microprocessor 115 byinterrupt, a watch dog timer may be employed to periodically wakemicroprocessor 115 to poll the proximity sensing system, e.g., at a rateof five times per second.

Electrostatic Discharge Protection

Operation of the electronic control circuitry of dispenser 1 may beadversely affected by the build-up of static electricity on feed roller33 and/or pressure roller 35. This is particularly so due to theproximity of the circuitry to the feed and pressure rollers. Advancementof paper or other insulative web materials across the rollers ordinarilywould result in the build-up of a considerable amount of staticelectricity on the rollers, thus placing the electronic controlcircuitry at risk of malfunction or damage.

An approach utilized in dispenser 1 for avoiding electrostatic dischargebuild-up on feed roller 33 and pressure roller 35 is now described withreference to FIG. 4. In accordance with the teachings of co-pending,commonly owned U.S. patent application Ser. No. 09/966,124, filed Sep.27, 2001, a conductive path may be formed by a wire, cable, metal strapand/or other conductor that extends from pressure roller 35 to adispenser supporting structure (e.g., a mounting wall). The supportingstructure may act as a local ground for discharging static electricitygenerated as web material (typically, but not necessarily, paper) ispassed through feed nip 37.

As illustrated in FIG. 4, pressure roller 35 may include a pair ofopposing support pins 261 (one shown) protruding outwardly from itsopposite ends, which serve to rotatably mount pressure roller 35 betweenside chassis members 5, 7. Pins 261 are preferably formed of metal,e.g., aluminum, or other highly conductive material, as is roller 35itself. A wire, cable, metal strap, etc. may be used to establish aconductive path which extends from roller pin 261 to a terminal, such asa screw or spring contact, that can be connected to a wall or othersupporting structure upon which dispenser 1 is mounted. Metal pin 261and metal pressure roller 35 complete the conductive path from thesupporting structure (e.g., wall) serving as a local ground, to feed nip37, whereby static electricity built-up on the rubber or like insulativegripping surface of feed roller 33 may be continuously discharged.

In order to provide a reliable, uninterrupted contact between a wire 263extending to the rear side of back panel member 11 and rotatablepressure roller pin 261, a metal strap 265 forms a contact arm that isspring biased into sliding contact with an outer circumferential surfaceof pin 26. The contact arm thus remains in contact with pin 26 as itrotates. Strap 265 is secured within right side chassis member 5 by apair of guides 267. Contact arm is elastically bent around guides 267 toform a leaf spring serving to bias the end of the thus formed arm intoreliable sliding electrical contact with roller pin 261. An opposite endof metal strap 265 connects with wire 263. Wire 263 is threaded along anouter perimeter of right side chassis member 5 to a back side of backpanel member 11 where it may be connected to the dispenser supportstructure (e.g., a wall), such as by a screw or spring contact.

Use of elongated conductors, such as wire 263 and metal strap 265, isjust one of many possible approaches for providing a conductive pathfrom roller 265 to the dispenser support structure. In lieu of aseparate wire or like discrete elongated conductor, the desiredconductive path could be established by interconnected metal or otherconductive structural components incorporated into or directly formingchassis assembly 3 and/or back panel member 11. In the event thedispenser support structure is highly insulative (e.g., a ceramic tilewall), it has been found desirable to provide an increased contactsurface area, such as through use of a foil or metal plate placed incontact with the supporting structure.

Dispenser Operation Control Logic

Referring now to FIGS. 21A and 21B, exemplary control logic foroperation of towel dispenser 1 is described. Control may begin with thedetection of an open cover or towel request, at step 267. If the coveris closed and a sheet request occurs, such as by detection of a hand byproximity sensing system 249, control proceeds to step 269 where it isdetermined if a towel segment is present in discharge chute 41 (see FIG.12), that is, if a previously fed towel has not been torn off. If atowel is present, control returns to step 267; control loops betweensteps 267 and 269 until a towel absent condition is detected. Once atowel absent condition is detected in step 269, control proceeds to step271 where a sheet detection timer is initialized. If a “sheet hanging”mode is selected, the sheet request check of step 267 is skipped.

In following step 273, feed motor 49 is started in the forward feeddirection to attempt a first interval of sheet advancement. Control thenproceeds to step 275 where a check is made to see if a leading edge ofsheet is detected. As has been described, a leading edge may bedetermined based upon a transition from a web present to a web absentcondition, at either one of sensors 111, 113. Upon detection of aleading edge, a counter associated with sheet displacement sensor 135 isinitialized, in step 277. In step 279, feed motor 49 continues to runfor a predetermined (second) dispense interval, whereby a leadingsegment of sheet material is fed out to a position where it may beremoved by a user. This may be carried out by counting the number ofpulses of displacement detector 135 and comparing the count accumulated(from the initialization of step 277) with a preset count valuecorresponding to the sheet segment length. In particular, the presetcount value is set such that it, together with the amount of sheetdisplacement that occurs (in step 273) prior to initialization of thesheet displacement detector, provides a total displacement serving toposition successive tear lines 19 within discharge chute 41, downstreamof the feed mechanism but upstream of the sensors 111, 113. As has beendescribed, the preset count value may be an adjusted count valueobtained by subtracting from the desired displacement a predicted“overshoot” of the feed mechanism once the motor is turned off. Althoughvariable, the pre-initialization feed-out of sheet material preferablynominally equals one-half of the distance between the feed mechanism andsensors 111, 113, based upon a target placement of successive tear linesmidway between the feed mechanism and sensors 111, 113.

Motor operation is continued in step 279 until the cumulative countvalue reaches the preset count value. In step 81, sensors 111, 113 arepolled to detect removal of the dispensed sheet segment by a user.Control loops at step 281 until removal of the dispensed sheet isdetected. Although not illustrated, microprocessor 115 may implementsleep modes to reduce power consumption during prolonged periods ofinactivity, as has been described. If removal of the dispensed sheetsegment is detected, control flow returns to Start.

If, in step 275, a leading edge of the sheet is not detected, the sheetdetection timer initialized in step 271 is decremented, in step 283, andthen checked to see if it has timed out, in step 285. So long as thesheet detection timer is not timed out, control proceeds to step 287where a check for detection of a leading edge is once again carried out.If a leading edge is not detected, control loops back to step 283. If aleading edge is detected, control proceeds to step 277, and thereafterin the manner as has been described.

If, in step 285, the sheet detection timer has timed out, controlproceeds to step 289 where a first feed transfer is attempted, byactuation of the feed transfer mechanism. Then, in step 291, the sheetdetection timer is reinitialized. Next, in step 293 (FIG. 21B), sensors111, 113 are once again checked to see if a leading edge of towel hasbeen detected. If yes, control returns to step 277 (FIG. 21A) andthereafter proceeds as has been described. If not, the sheet detectiontimer is decremented, in step 295 and checked to see if it has timedout, in step 297. So long as it has not, control proceeds to step 299where another check is made for detection of a leading edge. If aleading edge has been detected, this indicates that the first feedtransfer attempt was successful, and control returns to step 277 (FIG.21A). From there, control proceeds as has been described.

If a leading edge is not detected in step 299, control loops back tosheet detection timer decrementing step 295 and time-out detection step297. If a leading edge is not detected before the sheet detection timertimes out, control proceeds to step 301 where a second transfer attemptis carried out, by actuation of the transfer mechanism. Next, in step303, the sheet detection timer is reinitialized and another check fordetection of a leading edge of towel is made, in step 305. Upondetection of a leading edge, control returns to step 277 (FIG. 21A) andproceeds as has been described. If a leading towel edge is not detectedin step 305, the sheet detection timer is decremented in step 307 and acheck is made in step 309 to see whether the sheet detection timer hastimed out. So long as it has not, another check for a leading edge ismade in step 311. If a leading edge is detected, control returns to step277 (FIG. 21A) and thereafter proceeds as has been described. If not,control loops back to step 307 and then step 309. Once it is detected,in step 309, that the sheet detection timer has timed out, the systemassumes that the roll material within the dispenser is depleted, or thata malfunction has occurred. Accordingly, control proceeds to step 313(FIG. 21A) where feed motor 49 is stopped and LED indicator light 153 isblinked.

If a cover-open condition is detected in step 267, this indicates thatthe dispenser is being serviced, such as by an attendant replenishingthe dispenser and setting up the web material for transfer into feed nip37 (step 315). The program pauses at step 317 until a cover closure isdetected, whereupon control proceeds to step 271, and thereafter as hasbeen described.

In the above exemplary control embodiment, upon closure of cover 13 thedispenser waits for a sheet request signal before dispensing a sheetsegment. Alternatively, a sheet segment is immediately dispensed uponthe cover being closed (whether or not the “sheet hanging” mode isselected). With reference to FIG. 23, an advantage of this system willnow be described. If cover 13 of dispenser 1 is opened while a leadingsheet segment extends out of the discharge opening, when the cover isagain closed a leading portion 319 the leading segment may become lodgedbetween the inside of cover 13 and the bottom side of middle chassismember 9. When this happens, the leading segment may not protrude fromthe discharge opening sufficiently to be easily grabbed by a user orattendant. By automatically carrying out a dispense operation upon coverclosure (notwithstanding that web sensors 111, 113 detect the presenceof sheet material), a sufficient amount of sheet material will beadvanced out of the dispenser to form a sheet material loop 321 that mayreadily grasped and pulled-on to free lodged leading portion 319. Inaddition, an attendant receives immediate feedback indicating that theroll material is properly loaded and the dispenser is operatingproperly.

Relatedly, the dispense amount of an initial dispense operationfollowing a feed transfer operation is preferably adjusted (decreased)to compensate for the effective shortening of the leading segmentresulting from transfer bar 147 (or 200) pressing the leading portion ofweb 18 into nip 37 (see, e.g., FIGS. 15 and 16B). As seen clearly inFIG. 16C, this action typically will form a folded-over edge portion 323which is carried around the feed roller and into the discharge chute (41or 41′). As a result, web sensors 111, 113 will detect the fold-line 325of folded-over edge portion 323 as the free leading edge segment, andwill trigger (at that point) the second predetermined interval ofadvancement, to dispense the leading sheet segment and properly placethe adjacent tear line in the discharge chute (41 or 41′), upstream ofsensors 111, 113 and downstream of the feed mechanism. Since the firstsegment is effectively shortened by the fold-over amount, e.g., 1 inch,the predetermined second interval of advancement is preferablycommensurately shortened for this initial cycle, so as to assure properplacement of the adjacent tear line in the discharge chute.

In the above-described control embodiments, a routine may be included toprevent more than a predefined number of sheets from being dispensedwithin a specified time interval. If more than this predefined number ofrequests is made, the controller may be programmed to ignore the requestuntil the lapse of a timer. So, for example, if more than three requestsare made in a ten second period, the processor can wait until theexpiration of the ten second interval or for the expiration of a new tensecond interval after the third request. This provides an additionaldispenser abuse deterrent.

The present inventions have been described in terms of preferred andexemplary embodiments thereof. Numerous other embodiments, modificationsand variations within the scope and spirit of the appended claims willoccur to persons of ordinary skill in the art from a review of thisdisclosure.

1. A dispenser for dispensing flexible sheet material, comprising: asupport for rotatably supporting a roll of sheet material; a feedmechanism for advancing the sheet material out of the dispenser; a drivemember for driving the feed mechanism, said drive member being movablymounted for movement into and out of engagement with said feedmechanism; and a hold mechanism for locking said drive member in a firstposition of engagement with said feed mechanism, said hold mechanismbeing manually releasable to permit said drive member to be readilymoved out of engagement with said feed mechanism to a second position bytool-free finger operation and without detachment of said drive memberfrom its movable mount, wherein said drive member remains disengaged insaid second position without user applied force when said hold mechanismis released.
 2. The dispenser of claim 1, wherein said drive member isrotatably movable into and out of engagement with said feed mechanism.3. The dispenser of claim 1, wherein said feed mechanism includes a feedroller and a spur gear connected to said feed roller, and said drivemember comprises a worm gear for engaging said spur gear.
 4. Thedispenser of claim 1, wherein absent a jam said feed mechanism is freelyrotatable when said drive member is disengaged from said feed mechanism.5. A method of removing a jam from a dispenser for dispensing flexiblesheet material, the method comprising: detecting a sheet material jam;disengaging a drive mechanism of said dispenser from a feed mechanism ofsaid dispenser; clearing said jam from the path of the feed mechanism byrotating said feed mechanism while it is disengaged from said drivemechanism; and reengaging said drive mechanism with said feed mechanism;wherein said step of disengaging includes moving a motor and acorresponding drive shaft of said drive mechanism together as a unit todrivingly disengage said drive shaft from a locked position ofengagement with said feed mechanism, the motor and drive shaft of saiddrive mechanism are rotated as a unit to drivingly disengage said driveshaft from said feed mechanism, and the step of disengaging includesmanually unclipping a spring arm from a retention clip.
 6. A dispenserfor dispensing flexible sheet material, comprising: a support forrotatably supporting a roll of sheet material; a feed mechanism foradvancing the sheet material out of the dispenser; a drive member fordriving the feed mechanism, said drive member being movably mounted formovement into and out of engagement with said feed mechanism; and a holdmechanism for locking said drive member in engagement with said feedmechanism, said hold mechanism being manually releasable to permit saiddrive member to be moved out of engagement with said feed mechanism;wherein said hold mechanism is manually releasable by finger operationand said hold mechanism comprises: a retention clip; and a spring armfor selectively snapping into engagement with said retention clip. 7.The dispenser of claim 6, wherein said drive member forms part of adrive mechanism including a motor for driving said drive member, saiddrive mechanism being movable as a unit into and out of engagement withsaid feed mechanism.
 8. The dispenser of claim 7, wherein said drivemechanism is rotatable as a unit into and out of engagement with saidfeed mechanism.
 9. The dispenser of claim 7, further comprising acarrier retaining said drive mechanism for movement as a unit into andout of engagement with said feed mechanism.
 10. The dispenser of claim7, said motor being fixedly attached to said drive member by a driveshaft.
 11. The dispenser of claim 10, wherein said drive membercomprises a worm gear.
 12. A dispenser for dispensing flexible sheetmaterial, comprising: a support for rotatably supporting a roll of sheetmaterial; a feed mechanism for advancing the sheet material out of thedispenser; a drive member for driving the feed mechanism, said drivemember being movably mounted for movement into and out of engagementwith said feed mechanism; a hold mechanism for locking said drive memberin a first position of engagement with said feed mechanism, said holdmechanism being manually releasable to permit said drive member to bemoved out of engagement with said feed mechanism to a second position ofdisengagement; a carrier retaining said drive mechanism for movement asa unit into and out of engagement with said feed mechanism; wherein saidhold mechanism is manually releasable by finger operation, said drivemember forms part of a drive mechanism including a motor for drivingsaid drive member, said drive mechanism being movable as a unit into andout of said first position of engagement with said feed mechanism, saidcarrier being rotatably mounted for rotating said drive mechanism intoand out of said first position of engagement with said feed mechanism;and wherein said drive member remains disengaged in said second positionwithout user applied force when said hold mechanism is released.
 13. Thedispenser of claim 12, said carrier comprising: a motor chamber forretaining said motor; a drive member chamber disposed adjacent to saidmotor chamber for retaining said drive member; and a wall structureseparating said motor chamber from said drive member chamber.
 14. Thedispenser of claim 13, wherein said carrier defines a port allowingingress and egress of at least a portion of said feed mechanism, forengagement of said feed mechanism with said drive member.
 15. Thedispenser of claim 14, wherein said drive member comprises a worm gear,said feed mechanism includes a feed roller and a spur gear connected tosaid feed roller, and said spur gear at least partially enters saiddrive member chamber to engage said worm gear; wherein said worm gearengages said spur gear in a uni-directional manner to prevent overdriveof said motor.
 16. The dispenser of claim 13, wherein said motorincludes a drive shaft that extends through said wall structure and isfixedly attached to the drive member.
 17. The dispenser of claim 16,further comprising a retaining structure opposed to said wall structurefor rotatably supporting said drive shaft, said drive member beingretained between said retaining structure and said wall structure.
 18. Adrive mechanism assembly for selectively engaging with and driving afeed mechanism of a flexible sheet material dispenser, said drivemechanism assembly comprising: a motor having a drive shaft; a drivemember attached to said drive shaft, for drivingly engaging said feedmechanism while in a first position of engagement and a carrierretaining therein said motor and drive member, said carrier including arotatable mounting member for rotatably mounting said motor and drivemember to a dispenser chassis for rotation as a unit into and out ofsaid first position of engagement; a hold mechanism for locking saiddrive member in said first position of engagement with said feedmechanism, said hold mechanism being manually releasable to permit saiddrive member to be moved out of said first position of engagement withsaid feed mechanism to a second position of disengagement; wherein saidhold mechanism is manually releasable by finger operation and said holdmechanism comprises a first engagement member for engaging acorresponding second engagement member.
 19. The drive mechanism of claim18, wherein an axis of rotation of said rotatable mounting memberextends substantially orthogonally with respect to said drive shaft. 20.The drive mechanism of claim 18, wherein said drive member comprises aworm gear.
 21. The drive mechanism of claim 18, said carrier comprising:a motor chamber for retaining said motor; a drive member chamberdisposed adjacent to said motor chamber for retaining said drive member;and a wall structure separating said motor chamber from said drivemember chamber.
 22. The drive mechanism of claim 21, wherein saidcarrier defines a port allowing ingress and egress of at least a portionof said feed mechanism, for engagement of said feed mechanism with saiddrive member.
 23. The drive mechanism of claim 22, wherein said drivemember comprises a worm gear and said feed mechanism includes a feedroller and a spur gear connected to said feed roller, and said spur gearenters said drive chamber to engage said worm gear in said engagementposition.
 24. The drive mechanism of claim 21, wherein said motorincludes a drive shaft that extends through said wall structure and isfixedly attached to the drive member.
 25. The drive mechanism of claim24, further comprising a clip disposed on the end of said drive shaftfor preventing translation of said drive shaft out of said retainer. 26.The drive mechanism of claim 21, further comprising a retainingstructure opposed to said wall structure for rotatably supporting saiddrive shaft, said drive member being retained between said retainingstructure and said wall structure.
 27. The drive mechanism of claim 18,wherein said first engagement member comprises a spring arm for snappinginto and out of engagement with said corresponding second engagementmember, said second engagement member comprising a retention clip toreleasably hold said motor and drive member in said first position. 28.A method of removing a jam from a dispenser for dispensing flexiblesheet material, the method comprising: detecting a sheet material jam;disengaging a movably mounted drive mechanism of said dispenser from alocked first position of engagement with a feed mechanism of saiddispenser by tool-free finger operation and without detachment of saiddrive member from its movable mount, to a second position ofdisengagement in which said drive member remains disengaged in saidsecond position without user applied force when said hold mechanism isreleased; clearing said jam from the path of the feed mechanism byrotating said feed mechanism while it is disengaged from said drivemechanism; and reengaging said drive mechanism with said feed mechanism.29. The method of claim 28, wherein said step of disengaging includesmoving a motor and a corresponding drive shaft of said drive mechanismtogether as a unit to drivingly disengage said drive shaft from saidfeed mechanism.
 30. The method of claim 29, wherein the motor and driveshaft of said drive mechanism are rotated as a unit to drivinglydisengage said drive shaft from said feed mechanism.